Educate me on DP technical stuff (plus other questions)

[Slow4]

So I recently installed my 2.5" DP to compliment my Tru Dual and I just want to know more about how these DPs work; in general.

I already know that downpipes allow more airflow to flow smoothly from my engine to my exhaust, and also creating faster turbo spool-up. It also "reduces" the heat build-up on my k03s....

My questions are:

1. Now that I have a faster spool up, at what RPM do my K03s spool at? Is still @ 1850?
2. With just ECU mod, my peak boost would be around 4500, and would taper off soon after. With DPs + Exhaust, at what RPMs would I see peak boost?
2a. Would my boost constantly stay level @ 15psi well after 5K or would I just taper off as I did with just chip?
3. When driving today, I noticed that I would be able to stay in 1st, 2nd and 3rd longer than I did (during DD I would usually shift between 2100 and 2700rpms, upon ), why is that? (if this Q ties in with #1, tell me)
3a. I also noticed that when I hit 3K-3200rpms, my boost guage tells me I'm at 0psi, before if/when I hit 3K-3200rpms, I would boost ~5psi, why is that? (Again, if this Q ties in with #1, tell me)
4. Importantly, now with DPs on, how much more strain is put on my K03s?


On to off-topic questions...

1. If I buy the ECS dual clamps designed for pipes ranging from 53-60.5mm, it would clamp and offer a tight seal on my 2.25" exhaust, yes?
2. Same as above question but for my 2.5" DPs to be used with 65mm clamp?


Anywho...
In the next week or so, I'm going to put my stock exhaust and stock DPs in the classified section. I think I'm going to gut my stock DPs. Just wanted to let you gents(and ladies) know if you're looking for a stock exhaust and DPs

[Videlov]

Excellent questions I'm interested in getting answers also.

For 3a. though, it depends on the pressure you are applying to the gas pedal. So when comparing the stock with this new setup, you have to make sure you are applaying the same amount of pressure to the gas as you were when you were with stock DPs.

[Slow4]

Excellent questions I'm interested in getting answers also.

For 3a. though, it depends on the pressure you are applying to the gas pedal. So when comparing the stock with this new setup, you have to make sure you are applaying the same amount of pressure to the gas as you were when you were with stock DPs.

Hm...good point. I'll take notice of that when I'm in the car and report my findings. I do believe that I was at 1/2 throttle for question 3a. I'm still driving it like I did before, I haven't adjusted to the mods yet.

[GramCracker]

So I recently installed my 2.5" DP to compliment my Tru Dual and I just want to know more about how these DPs work; in general.

I already know that downpipes allow more airflow to flow smoothly from my engine to my exhaust, and also creating faster turbo spool-up. It also "reduces" the heat build-up on my k03s....

My questions are:

1. Now that I have a faster spool up, at what RPM do my K03s spool at? Is still @ 1850?
2. With just ECU mod, my peak boost would be around 4500, and would taper off soon after. With DPs + Exhaust, at what RPMs would I see peak boost?
2a. Would my boost constantly stay level @ 15psi well after 5K or would I just taper off as I did with just chip?
3. When driving today, I noticed that I would be able to stay in 1st, 2nd and 3rd longer than I did (during DD I would usually shift between 2100 and 2700rpms, upon ), why is that? (if this Q ties in with #1, tell me)
3a. I also noticed that when I hit 3K-3200rpms, my boost guage tells me I'm at 0psi, before if/when I hit 3K-3200rpms, I would boost ~5psi, why is that? (Again, if this Q ties in with #1, tell me)
4. Importantly, now with DPs on, how much more strain is put on my K03s?


On to off-topic questions...

1. If I buy the ECS dual clamps designed for pipes ranging from 53-60.5mm, it would clamp and offer a tight seal on my 2.25" exhaust, yes?
2. Same as above question but for my 2.5" DPs to be used with 65mm clamp?


Anywho...
In the next week or so, I'm going to put my stock exhaust and stock DPs in the classified section. I think I'm going to gut my stock DPs. Just wanted to let you gents(and ladies) know if you're looking for a stock exhaust and DPs

Your going to see the turbos spool a bit sooner because of reduced back pressure from the down pipes. This also means that your power band will come on a bit sooner than before (someone correct me if I'm wrong).

You might also see a bit more boost, like 1-2 psi, like I see. I spike to 17 and hold at 16-15. This is because of the better flow from the DPs.

There will be no added strain on your K03's. The best part about DPs is they take away some of the strain that is put on them by the back pressure of stock DPs.

Hope this helps a bit!

-Graham

[InLoveWithMyS4]

So I recently installed my 2.5" DP to compliment my Tru Dual and I just want to know more about how these DPs work; in general.

I already know that downpipes allow more airflow to flow smoothly from my engine to my exhaust, and also creating faster turbo spool-up. It also "reduces" the heat build-up on my k03s....

My questions are:

1. Now that I have a faster spool up, at what RPM do my K03s spool at? Is still @ 1850?
2. With just ECU mod, my peak boost would be around 4500, and would taper off soon after. With DPs + Exhaust, at what RPMs would I see peak boost?
2a. Would my boost constantly stay level @ 15psi well after 5K or would I just taper off as I did with just chip?
3. When driving today, I noticed that I would be able to stay in 1st, 2nd and 3rd longer than I did (during DD I would usually shift between 2100 and 2700rpms, upon ), why is that? (if this Q ties in with #1, tell me)
3a. I also noticed that when I hit 3K-3200rpms, my boost guage tells me I'm at 0psi, before if/when I hit 3K-3200rpms, I would boost ~5psi, why is that? (Again, if this Q ties in with #1, tell me)
4. Importantly, now with DPs on, how much more strain is put on my K03s?


On to off-topic questions...

1. If I buy the ECS dual clamps designed for pipes ranging from 53-60.5mm, it would clamp and offer a tight seal on my 2.25" exhaust, yes?
2. Same as above question but for my 2.5" DPs to be used with 65mm clamp?


Anywho...
In the next week or so, I'm going to put my stock exhaust and stock DPs in the classified section. I think I'm going to gut my stock DPs. Just wanted to let you gents(and ladies) know if you're looking for a stock exhaust and DPs

Answers:

1&2.) They should spool 2-300 rpms sooner and also achieve max boost about 2-300 rpms sooner on average.

2a.) Most SW tapers boost after about 5k rpms to about 11-13 psi on K03s, depending on how aggressive the SW is.

3.) I'm sorry, I don't understand your question. What do you mean by, 'you can stay in gear longer'?

3a.) By 3k rpm at WOT, you should be seeing max boost or damn near (approx. 16psi). Are you at WOT when you see 0psi? If you are at WOT, you have a boost leak IMO.

4.) With DPs on (and all things even, meaning you drive the same), you are theoretically putting less strain on your turbos because there won't be as much heat being held up behind them.

[Slow4]

Answers:

1&2.) They should spool 2-300 rpms sooner and also achieve max boost about 2-300 rpms sooner on average.

2a.) Most SW tapers boost after about 5k rpms to about 11-13 psi on K03s, depending on how aggressive the SW is.

3.) I'm sorry, I don't understand your question. What do you mean by, 'you can stay in gear longer'?

3a.) By 3k rpm at WOT, you should be seeing max boost or damn near (approx. 16psi). Are you at WOT when you see 0psi? If you are at WOT, you have a boost leak IMO.

4.) With DPs on (and all things even, meaning you drive the same), you are theoretically putting less strain on your turbos because there won't be as much heat being held up behind them.

Thanks man.

Well, to me it seems like I can stay in a gear particularly longer before needing to shift. For example, prior to install, I would have to shift from 3rd to 4th before 2500 (be somewhere near ~4/5psi)...now I can stay in 3rd way past 2500 and I won't boost anything over 1~2psi. (1/2 throttle is applied in this example)

Another question...would the rattle of the DPs be enough to loosen the connetion of the flanges of K03s and DPs? I know I tightened them enough but with those angles, I know its not TIGHT-TIGHT like a virgin!

[Videlov]

I guess what you are trying to say is that your gear ratio expanded? I don't know if expanded is the right word though.

[Jung]

what's forcing you to shift? am i missing something? you don't NEED to shift at any given point. what's forcing you to shift at 2500rpm? it doesnt really make much sense

[Slow4]

^^ I don't like the car being over 25/2700rpms, so I shift to keep it below that. I'm usually in 6th gear doing 50 or above.

I guess what you are trying to say is that your gear ratio expanded? I don't know if expanded is the right word though.

Something like that

[Videlov]

That's how I usually drive when waiting for the oil/turbos to warm up, I shift at like 2100 rpm with no boost at all. Just depends how you are applying the gas pedal cause you can reach redline without boosting at all.

[highPSI-S4]

Thanks man.

Well, to me it seems like I can stay in a gear particularly longer before needing to shift. For example, prior to install, I would have to shift from 3rd to 4th before 2500 (be somewhere near ~4/5psi)...now I can stay in 3rd way past 2500 and I won't boost anything over 1~2psi. (1/2 throttle is applied in this example)

Another question...would the rattle of the DPs be enough to loosen the connetion of the flanges of K03s and DPs? I know I tightened them enough but with those angles, I know its not TIGHT-TIGHT like a virgin!

I think you'll be fine, the best way to tell if things with the moda are diefferent is to really drive the car.
Exhaust sounds good by the way, That early morning we were on the way home and you punched it car pulled pretty good. Did you moniter your boost when you went WOT. Do a pull and find out how it drives, best thing to do is when your driving doing about 55-60 dropped it in 3rd and punch it, that should put you at about full boost in the rpm range and moniter the boost and how the car feels.

[AudiSportB5S4]

i think the gear thing he is referring to is like, you feel that the car is making more power in the same gear than before, which is 100% true when you install aftermarket DP's with more flow. a great example of this is when i went stage 3-, although the power numbers aren't that much more than a stage 2+ (287/336) how long it held that horsepower is what made me feel like I could hold out the gear longer. With K03s making the same numbers they may hit that number and hold it for 1000 RPMs say, where as I was making that number and holding it out until redline basically.... so when you add DP's which increase the flow you are getting a good amount of horsepower increase just by reducing the interference in the spool so you are probably holding peak power a bit longer

[Slow4]

i think the gear thing he is referring to is like, you feel that the car is making more power in the same gear than before, which is 100% true when you install aftermarket DP's with more flow. a great example of this is when i went stage 3-, although the power numbers aren't that much more than a stage 2+ (287/336) how long it held that horsepower is what made me feel like I could hold out the gear longer. With K03s making the same numbers they may hit that number and hold it for 1000 RPMs say, where as I was making that number and holding it out until redline basically.... so when you add DP's which increase the flow you are getting a good amount of horsepower increase just by reducing the interference in the spool so you are probably holding peak power a bit longer

Thats the answer I was looking for! I had the answer in my head but I wanted to confirm it with other ideas.

Thanks man.


Next question...how much does dynomat weigh and is it feasible to put it on our cars?

I love the sound of my exhaust but it can be deafening at times AND my GF doesn't like it. She says it reminds her of a civic (ironically enough, a civic with a fart can rolled up next to me and I did a good rev before the light turned red and rolled out....)

[AudiA4_20T]

you cant dynomat your exhaust, put another resonator in it, or tell the gf to man up

[Slow4]

you cant dynomat your exhaust, put another resonator in it, or tell the gf to man up

Nono, I want to know if I can dynomat the interior. Place them on the floor, under the mats, underneath the seats, in the trunk, etc.

[Evilevo]

Good god, that would add like 200 lbs!!! That shit is heavy!!

You should just get a quieter exhaust My Milltek is quiet

[ThirdStrike]

changing your exhaust setup in response to your gf's discomfort = FAIL.
hand her some ear plugs and tell her to keep her teeth together

[BITRBO]

You should just get a quieter exhaust My Milltek is quiet

My Milltek is quiet too

Almost too quiet sometimes, which is why I'm getting e-dumps w/ my DP's...

[speedydragon]

wow these are all reall great questions. unlike some of the usual questions we get on this forum "what is the best chip" questions. hah i had a great time reading the answers, kudos to the op and kudos for the guys who answered.

[Evilevo]

My Milltek is quiet too

Almost too quiet sometimes, which is why I'm getting e-dumps w/ my DP's...

Ya, i thought about that. But i have heard they fail. I just want to switch to a louder exhaust.

[obijohn22]

go to the FATMAT website. it is very good quality and excellent at sound dampening. It is a dynamat type material. It is leighter weight. You can also get it on ebay. I got 50sq feet and it weighed less than 20lbs. I did both sides of the rear deck and the trunk and all for doors and door cards with it. I just did a complete custom audio setup over the last month. I'll post some pics later in a different thread but anyhow, It greatly decreased the drone from my cat back as well as got rid of a lot of road noise which really helps the audio system deliver better detail. It was a lot of work but only a 20lbs gain and the results are great!

[Slow4]

go to the FATMAT website. it is very good quality and excellent at sound dampening. It is a dynamat type material. It is leighter weight. You can also get it on ebay. I got 50sq feet and it weighed less than 20lbs. I did both sides of the rear deck and the trunk and all for doors and door cards with it. I just did a complete custom audio setup over the last month. I'll post some pics later in a different thread but anyhow, It greatly decreased the drone from my cat back as well as got rid of a lot of road noise which really helps the audio system deliver better detail. It was a lot of work but only a 20lbs gain and the results are great!

Thanks Obi.

Was it hard putting in the fatmat inside the door area? How much did it all cost you?

[Ianxcom]

Is there a major difference between 2.5 and 3" DP on plain stage 1? Is there an advantage to each?

[Ianxcom]

Is there a major difference between 2.5 and 3" DP on plain stage 1? Is there an advantage to each?

Also i plan on using my stock exhaust.
Which DP should i get? Stock with gutted piggies or aftermarket?
Is the gain still 20hp with piggies and stock exhaust?
I kinda figure since i want to keep my stock exhaust for stock sound the difference between the two DP'd would be minimal if any. Ami right?

[Dimcorner]

Thanks Obi.

Was it hard putting in the fatmat inside the door area? How much did it all cost you?

I have installed Dyanamat on my Mazda3 and the road noise went down quite a bit. I would say I evenly slapped about 30lbs of the stuff on the car.

1. I don't know if FATMAT has an aluminum backing, but if it does, watch your fingers. It cuts skin rather easily.

2. Install it when it's warm outside. Makes it a little more pliable and helps it be sticky.

3. Use a roller if you have it. You want to avoid air pockets.

Other than that, the hard part is to get the coverage you want. They come in sheets/rolls and your car is not exactly a flat surface. I ended up cutting some interesting shapes to cover the trunk of the Mazda3.

[jerodmetcalf]

Also i plan on using my stock exhaust.
Which DP should i get? Stock with gutted piggies or aftermarket?
Is the gain still 20hp with piggies and stock exhaust?
I kinda figure since i want to keep my stock exhaust for stock sound the difference between the two DP'd would be minimal if any. Ami right?

You will gain more power by pairing a cat-back with downpipes. I just had SSAC downpipes with stock cat-back and it didn't sound too great. Louder than stock but it had some sort of rattle between 2400 and 2800 rpms that was solved when I replaced the cat-back. I just added the rest of the SSAC setup and it definately made more power and I like the sound more but it is louder.

[Ianxcom]

You will gain more power by pairing a cat-back with downpipes. I just had SSAC downpipes with stock cat-back and it didn't sound too great. Louder than stock but it had some sort of rattle between 2400 and 2800 rpms that was solved when I replaced the cat-back. I just added the rest of the SSAC setup and it definately made more power and I like the sound more but it is louder.

Oh god i hate that rattling sound. I definately dont want that.

The thing is im not looking for the most power I just want a Stock sound with relieved backpressure from the turbos and a little more pressure. If i ever were to get an exhaust I am probably going to get the Vibrant because of the stealthness but i really dont want to.

[quattroSD]

Phenominal analysis and fantastic questions.
That is all.

[Slow4]

Oh god i hate that rattling sound. I definately dont want that.

The thing is im not looking for the most power I just want a Stock sound with relieved backpressure from the turbos and a little more pressure. If i ever were to get an exhaust I am probably going to get the Vibrant because of the stealthness but i really dont want to.

To answer your previous question and put your mind at ease, gut your stock DPs. Not only will it relieve that backpressure and heat behind the turbos, it'll give you a killer exhaust note that will make people turn their heads and think "err, thats not a STi....what is it?"


As for me, my turbo flanges-to-DP flanges are still not tightened ALL the way due to some complications on ONE particular stud on the turbo flange. Under pressure of accelerating in low gear, I hear that annoying hissing noise emitting from the loose space between the flanges...I WILL get this fix soon.

[Ianxcom]

To answer your previous question and put your mind at ease, gut your stock DPs. Not only will it relieve that backpressure and heat behind the turbos, it'll give you a killer exhaust note that will make people turn their heads and think "err, thats not a STi....what is it?"


As for me, my turbo flanges-to-DP flanges are still not tightened ALL the way due to some complications on ONE particular stud on the turbo flange. Under pressure of accelerating in low gear, I hear that annoying hissing noise emitting from the loose space between the flanges...I WILL get this fix soon.

So 2.5 and 3" wouldnt make any difference over my gutted stock 2.25" when i use stock exhaust? Good to know.

[Slow4]

So 2.5 and 3" wouldnt make any difference over my gutted stock 2.25" when i use stock exhaust? Good to know.

To that question; not a big noticeable difference. I mean, you can go out and have people graph the 2.25" piggies, the 2.5" DPs, the 3" DPs and there won't be a BIG NOTICEABLE difference in performance.

Save the money, drill holes and create new life for your S. I just didn't have the time to do all that so I bought them used off Volks88.

Also...if you had chosen to got 2.5 or 3, you'd have to buy couplers to attached the 2.5/ to the stock 2.25 exhaust and yea...just stick to the the stock DPs.

[Ianxcom]

Thanks. That sounds like the best/cheapest way to go. I was thinking of getting them from VAST. Do they drill holes or gut the whole precat?

[Rated S]

You will gain more power by pairing a cat-back with downpipes. I just had SSAC downpipes with stock cat-back and it didn't sound too great. Louder than stock but it had some sort of rattle between 2400 and 2800 rpms that was solved when I replaced the cat-back. I just added the rest of the SSAC setup and it definately made more power and I like the sound more but it is louder.

Mine didn't sound bad at all when I had piggies and cut off my middle resonator on my stock exhaust. It didn't sound as good as with my Twin2 now, but I wasn't bad at all:


http://www.youtube.com/watch?v=6vAHelwPU6c