vast piggie pipes or FI downpipes

[drew]

i really want to complete my catback as it is way too mellow for me. the vast pipes are less then half of what the FI downpipes cost.

i am not sure which would be better for performance and sound. can anybody shed some light on this?

is it worth the extra money to get the FI downpipes?

i really can't decide on what to go with...

[91gl]

Get the piggies, having no cats makes a huge difference in performance

[drew]

Get the piggies, having no cats makes a huge difference in performance

the vast piggies for the v8 s4 gut the pre-cat, they still keep the main cat...

do you think it is still better?

what i am confused on is that my FI catback is 2.5 inch and i believe the FI downpipes are also 2.5 inch with less bends then the piggie pipes...the piggies are also stock diameter

[AudiOso]

If you do a search you can find a write-up that Justincredible did on downpipes and he talks about piggies. It's some good reading that really sheds light on the various options available for downpipes and where there are gains to be made.

[drew]

If you do a search you can find a write-up that Justincredible did on downpipes and he talks about piggies. It's some good reading that really sheds light on the various options available for downpipes and where there are gains to be made.

yeap i've read that one...just wanted to see if more people have some experience with this...

[joeycuccaro]

yeap i've read that one...just wanted to see if more people have some experience with this...

ill be getting the VAST piggies after reading that thread. I was going to get the F.I DP's to complete my setup but for the same performance id rather save the money.

[drew]

ill be getting the VAST piggies after reading that thread. I was going to get the F.I DP's to complete my setup but for the same performance id rather save the money.

cool...i am looking forward to hearing your impressions.

[Justincredible]

Drew,

I am just one of many people that did the Vast Dp's and did a write up on it. Several people before me have them. The issue behind me doing all the research was the opportunity to try all 3. The milltek's and both versions of the Piggie's

There are always going to be debates about bends and dimensions. The stock Dp's are almost the same as the milltek Dp's as for the FI they are great Dp's. They have bigger dia in some spots BUT they still have the pre cat.

With out saying anything more then this. My car has piggies (cat less) and I have the strongest 1/4 mile MPH to date. So I would say that should dispel the myth on size and bends etc etc....This analogy is not meant to be a end all to every debate. It is just meant to be a point of reference as to the possible power difference given pipe size and bends

[drew]

BUT they still have the pre cat.

thats what bothers me about the FI downpipes...i wish they moved the cat further downstream...

[Justincredible]

They do a good job of moving it. The FI Dp's are a great piece. I have always thought they were one of the best Dp's you can get. But if money Vs. performance is the issue then piggies are the way to go. If you have the money and want a real nice set of Dp's then the FI are a great choice.

[drew]

They do a good job of moving it. The FI Dp's are a great piece. I have always thought they were one of the best Dp's you can get. But if money Vs. performance is the issue then piggies are the way to go. If you have the money and want a real nice set of Dp's then the FI are a great choice.

thanks for the advice

[drew]

one more thing justin, in terms of sound what do you think will sound better (more aggressive) with my catback...the FI downpipes or the vast pipes with the gutted precat but main cat still in place?

[Justincredible]

in my experience all the cars Ive listened to the exhaust on, all have the same problem...That is you can still hear the motor whine over the exhaust note. Go search almost all the exhaust clips on line. In person it is even worse.

with the milltek's and the piggies with the pre cat in I could still hear the motor. After the removal of the pre cat the exhaust was the more dominate noise.

IMHO it seems to me that the pre cat is not only a big restriction but also a large silencer.

[jaybquick@JHM]

We put piggies (did it in house to VASTs specifications) on a local customers car with good gains. He already had a cat back and it woke the car up through the whole RPM band. We did plenty of before and after logging to verify an increase in acceleration rate all over the power band. No dyno numbers and no comparisons with another downpipe on the same car unfortunately. Maybe down the road. For the money it is definitely worth it.

I really think the pre cat is a bigger cork than the main cats. I am still baffled why most aftermarket DPs for these cars keep the pre cats but get rid of the main cats.

[notachance]

can someone describe what the sound is like? i have been debating this but i dont want it to be too loud and obnoxious. is there a terrible drone that comes along with it? i would be setting it up with a milltek non res catback.

[nonsense55]

one more thing justin, in terms of sound what do you think will sound better (more aggressive) with my catback...the FI downpipes or the vast pipes with the gutted precat but main cat still in place?

My car is in the shop now getting the precats gutted and a new LeBree catback! I hope to get it back soon and will glady post my results.

[91gl]

can someone describe what the sound is like? i have been debating this but i dont want it to be too loud and obnoxious. is there a terrible drone that comes along with it? i would be setting it up with a milltek non res catback.

with an x-pipe and resonators, think along the lines of Aston Martin

[ahwest]

not trying to thread jack, but does it affect smog with gutted pre-cat in CA?

[earhythmic]

not trying to thread jack, but does it affect smog with gutted pre-cat in CA?

from what I've read in Justincredible's thread, no. You'll still pass visual inspection, as it looks totally stock from the exterior. And you still have the main cat, so you'll be fine. According to the thread, cars before 2000 (is that date correct?) just had a main cat, and after that year they passed a clean air act, so that's why they added the pre cat as well. From what I've read, you WILL pass smog just fine.

correct me if I'm wrong?

Here it is from the other thread:

it is a complete plug and play part that has no CEL you still can pass emissions and the boost in performance Vs. the other Dp's

[Dompiece]

Question...after removing the pre-cat, does vast replace the main cat with a better flowing one? Also, what is involved in the modification to ensure no CEL?

[Justincredible]

Question...after removing the pre-cat, does vast replace the main cat with a better flowing one? Also, what is involved in the modification to ensure no CEL?

If you take a aftermarket cat and the stock B6 main cat. There is no reason to change out the stock. OEM cats perform so well it is going to be tough to tell the difference. Plus the OEM cat is made better much more sturdy.

The Vast modified Dp's don't get a CEL

There are two guys that got the Dp's after my thread that are in cally one of them said he passed smog with them if that helps

[jaybquick@JHM]

can someone describe what the sound is like? i have been debating this but i dont want it to be too loud and obnoxious. is there a terrible drone that comes along with it? i would be setting it up with a milltek non res catback.

The cat back on the car we did is resonated. It definitely resonates a little more in the 2000 rpm range. Not bad but you can tell a difference.

not trying to thread jack, but does it affect smog with gutted pre-cat in CA?

If done properly and the rear 02s are relocated behind the main cats then you will not get any codes. Visually an inspection shop cannot tell.

We have seen this done on many B5 S4s over the years and they still pass smog with flying colors. The reason being is that since the car is quattro they do not load the car on a dyno, therefore they just do an idle and 2500 free rev test. This is why they have never had a problem passing.

Technically this is illegal and we would NEVER condone such a thing.

California is extremely strict, if you even added an extra cat just ot try to help out, you would FAIL for visual.

I know plenty about this since I was a Licensed California smog tech for over 6 years.

[drew]

damn, i can't decide what to get...i spoke with Danny at Fast Intentions and he got me sold on his downpipes now LOL

[audmk3]

Question...after removing the pre-cat, does vast replace the main cat with a better flowing one? Also, what is involved in the modification to ensure no CEL?

I would greatly appreciate a response if anyone has an answer to this. I understand VAST uses a good flow Leistritz OEM, but is it a new unit or one recylced?

[dparm]

Get a quality high-flow cat and the performance hit is minimal.

[ItzDarrellS4]

although I dont have any experience with the piggies, i couldnt be happier with my FI dp's. woke the car up completely. and the SOUND, fawk yes

[drew]

downpipes ftw. i did go with milltek though. it sounds incredible. people stare like you wouldn't believe now

[idar]

This is mine with the piggies and supersprint exhaust (non-resonated). http://www.youtube.com/watch?v=xVO3ixThuAo

Upgrading to FI exhaust (also non-resonated) and will post a clip of that in the next few days.

[NYC_Legacy]

I thought FI sells a completely catless set of DPs, therefore the best option because it doesn't have any restricting cats and is 2.5"

[tylerS]

I thought FI sells a completely catless set of DPs, therefore the best option because it doesn't have any restricting cats and is 2.5"

they do, and they're awesome

[NYC_Legacy]

What about making the stock downpipes(piggies) Completely cat-less would their performance be a lot less than the FI DP set up

[jaybquick@JHM]

I would greatly appreciate a response if anyone has an answer to this. I understand VAST uses a good flow Leistritz OEM, but is it a new unit or one recylced?

Us and VAST both reuse the stock main cats. We have 2 sets of each modified and painted and ready to ship out today.

What about making the stock downpipes(piggies) Completely cat-less would their performance be a lot less than the FI DP set up

We have this option on our website to go completely catless. The performance is darn close to FI dps, it mainly affects the power above 5k rpm, but not a ton. -> http://www.jhmotorsports.com/shop/ca...roducts_id=395

[brad65ford]

Ok been doing some searching need some help boys. I'm going to install a cat back system this weekend and I have a spare set of Stock Dp's for my last b6s4. I've heard its a pain in the ass to remove the material from the pre cats but I want to try anyway. Now where would I want to place the bung for the o2 sensor. Does anyone have a photo of the location for the DYI'ers? JHM, is it safe to use the photos above for the locations?

[brad65ford]

Ok been doing some searching need some help boys. I'm going to install a cat back system this weekend and I have a spare set of Stock Dp's for my last b6s4. I've heard its a pain in the ass to remove the material from the pre cats but I want to try anyway. Now where would I want to place the bung for the o2 sensor. Does anyone have a photo of the location for the DYI'ers? JHM, is it safe to use the photos above for the locations?

Well I talked to my tuner today about possible tuning instead of relocating the o2 sensor. According to them I can now get the Stage 2 tune and this will help for removing the cell light I most likely will get. I've never gutted a cat but can't wait.

[drew]

i wonder why JHM paints the downpipes. kind of defeats the stealth factor of going with piggies....

[JohnnyAlQaeda]

Well I talked to my tuner today about possible tuning instead of relocating the o2 sensor. According to them I can now get the Stage 2 tune and this will help for removing the cell light I most likely will get. I've never gutted a cat but can't wait.

its a piece of cake, just make sure you wear a mask so you dont breathe that shit in.

[brad65ford]

its a piece of cake, just make sure you wear a mask so you dont breathe that shit in.

Cool, well after talking to my buddy he is not worried about removing them ourselves. My only consern is how long can I drive with the cell light on? My tuner said it might take a couple days once they get the ecu computer code. So I would have to drive for a week with the cell light on, anybody know how bad it is?

[D.K]

My CEL has been on since around September when I installed my DPs. No problems aside from the light being lit. If your CEL is on due to rear O2 sensors, it won't cause any problems with performance...or fuel consumption for that matter.

[Jdubya]

When I had my main cats removed I had them put the APR cat-less program on to get rid of the cel.

[brad65ford]

So what does the Cel light do then to the car performance, anything? Well I'll let you guys know how I made out. My last S4 I went with AWE dp's and they are almost 2k so this will be a big savings.