Help me with catback please!

[Espi]

Originally Posted by gpvecchi

I have another question: how much the stock center section affects performances?
I mean, is it better too keep the stock midpipe with its kinks and bends but good silencing properties and a more "open" axleback, or a catback with a little more restrictive muffler?

Catback mostly opportunity for weight savings over stock system. Any performance benefit I think is minimal at best and a bonus if any.

[gpvecchi]

Guys, can you PLEASE at least read my question? I did't ask how to make my exhaust quieter, but exactly the opposite!
The Apexi kit is as quiet as stock exhaust.
AND I'M NOT TALKING OF THE FRONT PIPE, BUT THE MID PIPE!!!!!!!!!!!!!
My thread is about catback, so please don't talk about the rest of the exhaust.

[Espi]

Catback is really up to your ear. Almost no performance gain so really up to you. If the stock midpipe with the STI axleback was too loud chances are anything full catback might be louder. Unless it's designed to be on the quiter side like the Greddy SP - I know its not on your list but something to consider.

[SCFD]

Originally Posted by gpvecchi

I forgot, I prefer a quiet exhaust at low revs, but a little growl when revving.

To get this, what you'll want is a big muffler that's also high-flowing (i.e. straight through or close).

[NLSP]

If there's anything that fills the spot between stock and STI muffler, I think it'll just be the Fujitsubo Authorize S (axle-back) since it's only a few dB more than stock. However, I couldn't find the STI axle-back dB specs anywhere, so not 100% sure.

I feel like any other brand of cat-back or axle-back will be louder. Fujitsubo (an OEM supplier) and STI (also rumored to be made by Fujitsubo) are as OEM+ as you can get IMO.

Part numbers:

• 360-23111 for Zenki
• 360-23132 for Kouki

[gpvecchi]

Thanks, Fujitsubo it is one of the best option.
Do you think that keeping the stock center section will be restrictive?

[NLSP]

Originally Posted by gpvecchi

Thanks, Fujitsubo it is one of the best option.
Do you think that keeping the stock center section will be restrictive?

For naturally aspirated applications, I don't think the stock mid-pipe is restrictive. I feel like most people want to change it because they usually change every other piece in the exhaust and they think it's weird to leave one OEM piece.

I haven't tested myself, but found 3 points of reference:

1) Supersprint - "We tested different setups. The mid-pipe doesn't give any power gain, as well as the rear muffler. The only way to gain real power on this car is to work on the front pipe and the headers."

2) Nameless Performance - Thought the same as above, so they never made a mid-pipe to go with their 2.5" axle-back. They only offer mid-pipe for their 3" exhaust intended for forced induction.

3) DSPORT magazine tested 11 exhausts on a stock car (9 cat-backs, including HKS, GReddy and 2 muffler deletes with stock mid-pipe). One of the muffler deletes with stock mid-pipe produced the most peak horsepower, so clearly the mid-pipe is not an issue.