DIY Exhaust Mod – Gain of 10+ HP!!!

[particlewave]

Slate - I put this off for the same reason. I finally wound up doing 9/16" holes about 10 months ago. The sound at idle is much deeper and throatier, and a general increase in roar over the RPM range with zero noticeable resonance. Overall, I'm very happy with the sound. I'm even considering enlarging the holes to 1" to get just a little more growl out of it.

I don't think there's much chance of getting a lot of resonance or that annoying "coffee can muffler" racket since you're only bypassing one chamber

[JAAY]

1" sounds glorious. No drone or resonance at all. I may take the car out tomorrow. I'll try and post a video. Stay tuned.

[chipmunk]

OK - here is the sound of the exhaust with 10mm, 13mm, and 15mm holes. Subtle difference in sound - the 10mm is a little more raspy and the 15mm a slightly deeper note. If you go larger I would image it will get even deeper.

Porsche Boxster 986 Crios Mod - YouTube

[jb92563]

Based on the great results I had when I installed the 2nd cat delete pipes on my top speed muffler, im thinking that doing the 2nd cat delete pipes with the stock muffler may also produce the great improvement in exhaust tone and throttle responsiveness.

Has anyone tried that?