AFE Twisted Steel cat pipes
 

https://afepower.com/afe-power-48-34...nnection-pipes

After ordering these in February, receiving them in April (apparently they're made to order), dropping them off at the coater (https://www.facebook.com/SSPowderCoating/) in May, I finally had them installed by the local Corvette specialty shop (https://www.facebook.com/CustomImageCorvettes/). I already have my factory exhaust manifolds ported/coated along with a Borla X-pipe and figured these would round out the exhaust system while still keeping things plenty livable on the street with the NPP.

Factory cat pipes w/DEI heatshields:
http://www.mitsustyle.com/photopost/...0606191838.jpg

AFE pipes before coating:
http://www.mitsustyle.com/photopost/...0406191623.jpg
http://www.mitsustyle.com/photopost/...406191623a.jpg

AFE pipes after coating:
http://www.mitsustyle.com/photopost/...0603191650.jpg

Here are some comparison pics of the pipe inlets and cat density showing, in theory, how much more restrictive the factory pipes are:

http://www.mitsustyle.com/photopost/...606191838a.jpg
http://www.mitsustyle.com/photopost/...606191838b.jpg

Vs.
http://www.mitsustyle.com/photopost/...406191623b.jpg

I only have a few miles on then so far to cure the coating, but no CEL yet (AFE claims it's a 50/50 chance). I've gotten on the car a bit and it definitely has some additional volume to it; same with start-up and idle. Tour mode while cruising still seems plenty tame for roadtrips though which is exactly what I wanted.

I have a tank of 93-octane right now so I'll get some logs off to my tuner (DiabLew) this weekend, then once that tank is gone I'll get it done again with the local 91 available in-town.


A few threads for reference:
exhaust manifolds - https://www.corvetteforum.com/forums...manifolds.html
X-pipe - https://www.corvetteforum.com/forums...-vs-corsa.html
DEI heatshields - https://www.corvetteforum.com/forums...ion-notes.html

Very nice! Can't wait for an additional review!

-JOsh

Nice, it would great to have a sound clip too

I didn't take any "before" sound clips so I don't think an "after" one would do anyone much good since the car sounds about the same, just with a little more volume. A little more bark to the exhaust note when you get on it or are decelerating.

I may try swapping the DEI cat shields on and see how they fit. Has anyone tried using them on an aftermarket high-flow cat? They fit the factory cats perfectly.

I'm considering catless downpipes; not a tune (aware of a CEL)... However, would Air/Fuel be affected enough where I'd require it ?

According to NorCalSS, he's not having any issues on customer cars running the stock tune and catless pipes other than having to run the Big Daddy angle foulers to prevent the CEL. I'm tuned already, and just want to make sure it's maximized for the new mods.

Here's the catless version of my AFE pipes: https://afepower.com/afe-power-48-34...nnection-pipes

I went for a nice drive today to get some good logs for my tuner and can confirm no strange smells, nothing stronger than stock odor, with these AFE high-flow cat pipes. Garage cold start, cold idle, driving windows up and down, gas station, then hot idle in the garage.

Kind of strange for just having dyno numbers for the C7 Z06 only. So I guess there are no concrete numbers to refer to on the C7"s?

I spoke with AFE's engineering team and they said the gains on the LT1 are about half of what they saw on the LT4 which makes sense. The C7 LT1 has an incredibly robust exhaust system from the factory so the gains aren't going to be as large as experienced on previous generations.

Thanks for the immediate reply. But they're advertising the C7 dyno information at 20 hp and 19 tq.....way more than half of the Z06. I just hope they could clarify that. Very interested

When I spoke with them we were talking ~20 whp for the LT4 and ~10 whp on LT1.

Here's their Z06 dyno chart which agrees to the +20:
https://afepower.com/media/catalog/p...1551224618.jpg

Will it still pass emissions testing?

OBDII scan like in Texas, yes. Actual tailpipe sniffer, not sure.

Thanks. I think NC is the same with obdII scan.

What is the reasoning on going with these over headers/catted x-pipe?

Mainly price, these are half the price of catted headers.

Also install is much easier - so if you are paying someone to install, the labor will be much cheaper.

And they're do it yourself.

Quite a few various reasons for me. I actually had a set of AFE PFADT Tri-Y headers w/cats but never installed them. I think they sound obnoxious, create too much underhood heat, warranty killer, emissions killer, and not compatible with the stock tune. All of these things were very important to me, especially while still under the factory 5/100 powertrain warranty. Frankly, I don't think I'm giving up much, if any, power either. Ported/coated exhaust manifolds + AFE cat pipes + Borla catless X-pipe. Another forum member and I did dyno tests at the same shop and saw identical WHP gains; I did ported/coated exhaust manifolds and he did ARH mid-length catted headers. Both saw +11whp. I saw +8wtq and he gained +14wtq. I'll easily exceed his overall gains now that I've added the AFE cat pipes. We both had the same Borla X-pipes. Best of all, I get the power gains while maintaining a tame exhaust note in Weather/Eco/Tour mode for roadtrips while staying emissions friendly and stock tune compliant for dealership visits.

Same reason I won't do anything that requires a tune. Something simple can ruin your day and you're out 20 grand putting in a new engine.

Kracka.....we really appreciate your information on this particular product in detail. It seems like this AFE pipe is on par with the ARH mids with a tremendous savings. Thanks sir