High-Flow Cats to match Supersprint headers

A5/S5/RS5
#1

I might just install the Supersprint Racing headers for the S5 3.0T while the car is in service mode and being serviced to much… So much to do…

The headers will be ceramic coated, the original heat shields do not fit anymore.

But now the question: High-Flow Cats, I find myself doubting between 100cpsi or 200cpsi.

100cpsi Tri-Metal

  • have a better flow (should), but I also read that for the 100cpsi core to hold up, they use bars to keep the core from collapsing under pressure. Which can lead to less flow.
  • APK/ TUV Check can cause problems with c02.
  • Read about degrading faster after 15k and smell goes up and CEL comes up.

200cpsi Tri-Metal

  • Nice flow
  • Most of them pass through the gas tests
  • No degradings found

How much of the issues with the 100cpsi cats are true for those of you who have installed and use them?

#2

From what I have seen in the past there isn’t really any hp gain from headers on the 3.0T this was tested in the past.

That’s not to say they make less hp. There just dosen’t seem to be any gain.

200 Vs 100.

If your getting cats put back in. Get the 200s. The 100s flow more but in most cases if your worried about 02 tests 200 are much better.

100s flow much better but don’t actually clean well as they never really get to maintenance temps and clean well. What I tend to see more times than not is that the 100s become clogged and fail.

#3

I heard the same thing justincredible said about the headers. There might be a slight improvement in a good header but overall Audi designed the exhaust header itself pretty darn good. The restriction is the Cats, but if you have to do emissions then you are stuck with something hanging off the back of the header. If nothing else, dependiing on your mileage and tuning state you may want to pull the front O2 sensors and inspect the cats with an inspection camera as they’ve been known to deteriorate and many times cause clogs in the exhaust. I’m running a Stage 2 tune on my S5 now, we’ll see how long the headers last. Sent the headers for my RS5 to JHM a few years ago to modify and remove the Cats, Jason said the Cats were shot and causing a restriction.

#4

Thanks Guys,

200cpsi it will be

#5

You will be happy. Just make sure to move them back to about where the transmission is. So you have them far enough away from the manifolds to now cause a stall point but not so far down stream that they cause a restriction