RAI Test Pipe and Downpipe Explained (Downpipes are on sale!)

[[email protected].]

I get a lot of PM's with questions regarding our test pipes and downpipes, so here is this to explain a bit.



In addition to all this, our Downpipes are currently on sale. Save $35!

[TFSI]

I have 034 HFC on tiptronic. does the downpipe fit right up? No plan to get exhaust, just the downpipe maybe

[TFSI]

or does your "downpipe" only comes in one piece with testpipe?
I was wondering if I can get the bottom pipe separately.

[FL-B7]

so this may be a dumb question, and im not bashing your product by any means, but:
what advantage does the downpipe add? on the diagram it looks like it just moves the bottle neck closer to where the exhaust would bolt up rather than having it right after the HFC/test pipe...from what ive learned in about fluid dynamics in physics class, so long as the diameter is reduced the flow rate is as well, it would just build back pressure a little bit less quickly...

[[email protected].]

so this may be a dumb question, and im not bashing your product by any means, but:
what advantage does the downpipe add? on the diagram it looks like it just moves the bottle neck closer to where the exhaust would bolt up rather than having it right after the HFC/test pipe...from what ive learned in about fluid dynamics in physics class, so long as the diameter is reduced the flow rate is as well, it would just build back pressure a little bit less quickly...

The larger diameter downpipe not only eliminates back pressure and turbulence, but it also provides more room for the exhaust to cool, thus increasing in density as it passes though. By the time it reaches the rest of the exhaust and passes though the last reducer, the bottle neck is essentially eliminated. The reduced back pressure allows the turbo to spool faster, and hold boost longer, maximizing its efficiency range.

[wootwoot]

Do you have a dyno with the 4" to 3" test pipe and downpipe combo? I would love to see the gains.

[[email protected].]

Do you have a dyno with the 4" to 3" test pipe and downpipe combo? I would love to see the gains.

last time we dyno'd the downpipe was last summer, and we picked up 20whp across the power band. this past winter we dyno'd the test pipe and picked up similar peak numbers, but conditions were more favorable and the gains weren't spread across the band like we saw with the downpipe.

[shiro1745]

last time we dyno'd the downpipe was last summer, and we picked up 20whp across the power band. this past winter we dyno'd the test pipe and picked up similar peak numbers, but conditions were more favorable and the gains weren't spread across the band like we saw with the downpipe.

I would be interesting to see a dyno sheet with your setup and let's say any other aftermarket setup out here (TP/HFC + Downpipe) so this way we could really see some facts. And of course if the gains are significant I'm sure a lot of guys here that already have different setups would consider this. I'm actually one of those. I'm running a VMR TP and Milltek catback

[[email protected].]

I would be interesting to see a dyno sheet with your setup and let's say any other aftermarket setup out here (TP/HFC + Downpipe) so this way we could really see some facts. And of course if the gains are significant I'm sure a lot of guys here that already have different setups would consider this. I'm actually one of those. I'm running a VMR TP and Milltek catback

Are you refering to the downpipe ore the test pipe in this case. We did a tp comparison when we released our test pipe.

Our TP vs Stage 1


In comparison, the ebay tp numbers:

[kristokes]

Btw Will, I got this PM regarding the RAI test pipe dyno numbers. The member wants to remain anonymous but I thought it would be best if I gave RAI the opportunity to answer it:

I didn't want to post in their thread and start any drama, but I wanted your thoughts on their dyno claims.

RAI claims 229TQ on a Stage 1 no TP and 248.6tq with a RAI TP added (+ 20tq), and now with the ebay TP dyno they claim it's only 233tq (that's only a 4tq difference over stage 1).

Just seems odd that the ebay or in my case VMR TP is only good for a 4tq increase. Thoughts?!? As I was always under the impression it was at least +20tq for even the VMR TP.

Don't want to post in their thread as I don't want to stir the pot. But like I said, even HFC's claim around 20tq. I don't dispute, it's a better design, but their numbers for non-RAI TP's or HFC's are alot lower than every other TP dyno I've seen. You seem to be pretty knowledgeable, so I wanted your thoughts, if I was looking at it the wrong way.

He is referring to this post: http://www.audizine.com/forum/showth...=1#post6161809 and the dyno graph in your previous post.

[[email protected].]

or does your "downpipe" only comes in one piece with testpipe?
I was wondering if I can get the bottom pipe separately.

Unfortunately not. Our downpipe would replace both your HFC and stock downpipe in order to maintain the 3in diameter all the way though. Otherwise you'd still get that bottleneck at the HFC/DP flange.

[Insane_Audi]

do the bigger name exhausts such as AWE/APR bolt to the reducer?

isn't the only problem with this is finding an option(other than custom) that mates at that point in the exhaust?

[[email protected].]

Not so. most exhausts out there are meant to be used with the factory downpipe. after our reducer, there is a section of stock diameter tube. a simple slip fit and our downpipe bolts right up.

[Insane_Audi]

Not so. most exhausts out there are meant to be used with the factory downpipe. after our reducer, there is a section of stock diameter tube. a simple slip fit and our downpipe bolts right up.

oh ok, i knew there was some question when this downpipe was first released. so if someone were to buy this downpipe as well as an APR exhaust, they would have to clarify to only send them the "downpipe back" section, and not the whole catback?

[[email protected].]

oh ok, i knew there was some question when this downpipe was first released. so if someone were to buy this downpipe as well as an APR exhaust, they would have to clarify to only send them the "downpipe back" section, and not the whole catback?

yes this is correct. and if anyone has an exhaust that came with the downpipe, our Testpipe/HFC solution will work for them.

[Insane_Audi]

yes this is correct. and if anyone has an exhaust that came with the downpipe, our Testpipe/HFC solution will work for them.

thanks for the clarification, will probably order soon

now stop drawing pictures and sell me a K0R, or else!

[MR.H]

This should go into the stickied B7 A4 newb section. Well done sir.

[GarrettReid]

Would this fit a CVT? Would anything from RAI fit?

[mauismile]

Would this fit a CVT? Would anything from RAI fit?

I want to now this also?? Or would just the test pipe work??

[kristokes]

RAI's method and logic makes sense! It's just too bad my current exhaust set-up is no longer a slip-on fit after the downpipe; it bolts up to a flange now.

I can't see the RAI downpipe being easy to install on jack stands as there is limited clearance to play with a long 1 piece set-up - you would definitely need to be raised a little bit higher so using a lift would be wise for all the DIYers.

[[email protected].]

RAI's method and logic makes sense! It's just too bad my current exhaust set-up is no longer a slip-on fit after the downpipe; it bolts up to a flange now.

I can't see the RAI downpipe being easy to install on jack stands as there is limited clearance to play with a long 1 piece set-up - you would definitely need to be raised a little bit higher so using a lift would be wise for all the DIYers.

Stokes, we could probably do a custom flange adapter if you needed. Let me know if you are interested.

Also, while the tp/dp are all once piece, there is a v-band split between the cat delete section and the rest of the downpipe. you can install the upper section from the top of the car and the rest from the bottom. ultimately a lift would be ideal, but you can probably get away with jack stands or a decent set of ramps if your not too low.

[jmarch1122]

I just ordered this last week, can i get the $35 back please?

[kristokes]

Stokes, we could probably do a custom flange adapter if you needed. Let me know if you are interested.

Sounds great Will

I'll send you specs of the flange when I'm ready to swap out my current set-up which includes your RAI test pipe. I just recently installed my current exhaust set-up so I don't want to change anything just yet.

[br8ker21]

Not sure if this was asked, but will this work with APR tune?

[[email protected].]

Not sure if this was asked, but will this work with APR tune?

yes, your tune won't be affected. you don't even have to have them code out the secondary 02.

[osnapitseric]

what kind of gains are we looking when we do the HFC + Downpipe route?

[[email protected].]

what kind of gains are we looking when we do the HFC + Downpipe route?

A few hp less than catless, but still right around a 20hp bump.

[B72.0T]

Nope their downpipe will not work with a CVT.

[[email protected].]

Sorry guys until we have a car in here to test fit one on, I can only advise CVT guys to pick up the test pipe.

[mauismile]

Sorry guys until we have a car in here to test fit one on, I can only advise CVT guys to pick up the test pipe.

Okay, so test pipes not on sale (for us CVT owners), only downpipes??

[GarrettReid]

Okay, so test pipes not on sale (for us CVT owners), only downpipes??

People with CVT's just got jizzed on by RAI so hard.

(me included)

CVT needs some lovin'

[Mc Suly]

Is it worth it too just get the RAI Downpipe rather than a custom exhaust 3" from turbo to tip???

-I know I asked this in the PM but asked around & keep getting different answers...
You said in the previous comments that most of the bottleneck affect is gone.

[[email protected].]

Is it worth it too just get the RAI Downpipe rather than a custom exhaust 3" from turbo to tip???

-I know I asked this in the PM but asked around & keep getting different answers...
You said in the previous comments that most of the bottleneck affect is gone.

I'd say about 90% of your gains will come from swapping out the downpipe vs doing the whole exhaust.

[Jay-Bee]

Any idea what this will sound like with stock DP back exhaust? I know just throwing on a TP makes it sound very raspy, will opening the DP up help with this?

A vid would be awesome, as I am considering this as my next mod before getting chipped this summer.

[jl87]

A vid would be awesome, as I am considering this as my next mod before getting chipped this summer.

X2 for sound clip of RAI's DP w/ HFC or TP combo on stock exhaust.

[A-BlacK_MambA-4]

I just ordered the TP/Downpipe combo today so once I get it installed I will try to upload a sound clip/video... And yes this will be installed with a stock exhaust from downpipe back... Thanks again to Will for all of his help on my purchase....

[jl87]

I just ordered the TP/Downpipe combo today so once I get it installed I will try to upload a sound clip/video... And yes this will be installed with a stock exhaust from downpipe back... Thanks again to Will for all of his help on my purchase....

Awesome. Thank you in advance

[Stea1th]

subscribed

[br8ker21]

I'm wondering how the RAI downpipe + Stasis exhaust would be...

[BladesBravo]

I'm wondering how the RAI downpipe + Stasis exhaust would be...

x2 on this, my future plans in the next 2-3 months. But...

Below I found a pic of the STaSIS manual exhaust (but from my understanding the exhaust for the tiptronic is just the same minus the DP). From where the exhaust connects to the DP it doesn't look like the RAI one will be able to plug in. Or am I looking at something wrong?

Pic pulled from http://www.audiction.com/audi-tuning...t-hfc-install/