I'm currently running the ultimate racing HF Cats with the APS 2.5 exhaust and am about to change the cats to APS test Pipes. Will it get much louder?
I love how quite my car is right now...

 

Honestly it is not much louder at all, I had helix test pipes for a while with my greddy evo2 and it was a perfect deep sound and not raspy at all... it poped but at High rpms.
This might get moved to intake and exhaust......

 

thanks, I posted here since I have a APS TT and it's a different volume once turboed

 

I think it depends your power levels

 

When I was n/a my test pipes were kinda loud and raspy. After going turbo I lost the rasp and it wasn't as loud.

 

I had Crawford cats and they sounded much better than my APS TT & APS test pipes with Nismo exhaust. I miss it and I'm considering going back to the Crawfords but with the 3" APS exhaust. I wonder if that would make up for the loss of flow from the cats?

 

Im running APS TT w/ Nismo exh. and testpipes and its not loud unless your on it. Then its loud but not obnoxiously loud.

 

APS TT w/Fujitsubo exhaust and testpipes and what he said ^^^^^^^

 

I had APS TT for 4 month w/ Cat's then went to test pipe. It is about 25-50% louder inside the car when you are on it, and about 100% louder when you are behind the car. If you are not on it ,than no one has any ideas.
Yet, you gain about 40-50 rwhp out of it (I did). Just remember w/ any mod, have the A/F ratio looked at. About 90% chance you will have to have them remapped w/ test pipes!! Your exahust runs about 100F cooler without them in too.
Be ready for soot to come out the back when you lay on it and your exhaust and rear end will get a lot more sooty.

 

+1 on the soot

 

I'm getting them installed as part of a retune so no worries there

 

I could barely tell a difference in the loudness of the idle from when I was N/A with cat's and Greddy exhaust to TT with test pipes and Greddy exhaust.

 

I have straight pipes now with the TN and basically straight back exhaust and is VEry Deep but not high pitched what so ever sounds perfect to me!

 

Don't know what you think the retune will do, but your tunner most likely will still set you A/F rich under load and you will not have the cat's to filter the soot anymore. Therefore, unless you get close to 14.7 on your A/F (which I don't think you want to do unless you don't like your engine) you will get soot.

 

I was referring to the map being off once the test pipes are installed.
I'm getting my boost upped and as part of that I'm installing the Test Pipes to have it tuned accordingly.
Nothing to do with Soot

 

Sorry - my bad. Misunderstood what you meant, yes get the tune after the test pipes.

 

Its only loud at WOT above 3000 rpm's, atleast for me it is.

 

Time to go 3.5" downpipes.

 

Yeap +1, on the mod, though I am wondering how the stainless steel will match with the cast steel of the turbine. Does anyone had problems with that? Meaning that due to differrent thermal expansion of the two materials there maybe a problem with the load on the bolts and nuts.

 

Has anyone done a comparison on the difference in power/spool with 3.5" vs 3" downpipes?