[Funnyman]

By looking at Pagani Zonda RR exhaust's full tube. Lengths seem to be calculated. If lengths wasn't an issue, they could be a lot shorter.
From what I readed, exhaust tube length is function of the opening/closing sequence of exhaust/intake valves and other things.

 

[03MRS]

I had a Magnaflow muffler immediately after the header. It was loud but I didn't need ear plugs. I'm not sure how many track hours I put on it, but I don't recall its sound-dampening performance degrading.

View attachment 80795

Yep, something like this!!!!! It will save me ALOT of weight, (which needs to be saved since I will have in there k24 and 6spd.

I do have PPE 4->1 headers for k24

Ideally I would like some easy to mount option to swap between this setup(pictured above) and one with PPE catpipe for emission test/maybe daily driving.

 

[Node]

I can tell you one thing I have confirmed. Loud exhaust is picked up by the knock sensor. I have seen timing adjustments on the OEM ECU just from a loud muffler. That may have been why you were down on power.

 

[dblotii]

I can tell you one thing I have confirmed. Loud exhaust is picked up by the knock sensor. I have seen timing adjustments on the OEM ECU just from a loud muffler. That may have been why you were down on power.

How do you know that the change in exhaust system (muffler) didn't actually cause incipient knock? Knock sensors should not be affected by outside noise.

Dave

 

[Funkycheeze]

Knock sensors are just microphones, so they can pick up external noise especially if transmitted through metal back into the engine, like a loud gearbox or road/suspension noise on a car with more solid mounts.

 

[Funnyman]

By experience right now, my MR-S got P0325 knock sensor issue.
Juste because exhaust tips touch the crash bar (crash bar's holes are not enough big).