Talk to me about exhaust diameter

ATR84 · Post by **ATR84** » Thu Aug 20, 2020 1:47 pm

I have recently been thinking about getting a 3 inch downpipe back custom exhaust made up but it got me thinking.

If the diameter of the header and downpipe is not 3 inch also, is there any point? Will you see any improvement? For reference I have a Mugen header on mine, don't know about the downpipe but assuming standard Type S which I understand is different to other Prelude downpipes. I then have a decat and a Skunk2 exhaust, I believe the Skunk2 is 2.36 inches in diameter.

If I do go custom what diameter would people recommend? Best for power but bearing in mind noise. I like it loud, but I want to be able to hear my music when on a longer journey.

Also, should I change my header and downpipe as well?

Anyone with experience of different set ups on their Prelude who can offer advice?

Post by **RattyMcClelland** » Thu Aug 20, 2020 4:56 pm

On your car I would go with a 2.5" exhaust.
No need to change the Mugen header or decat.

ATR84 · Post by **ATR84** » Thu Aug 20, 2020 5:22 pm

RattyMcClelland wrote: ↑
Thu Aug 20, 2020 4:56 pm
On your car I would go with a 2.5" exhaust.
No need to change the Mugen header or decat.

Thanks @RattyMcClelland , be good to know why that's your opinion though

Post by **RattyMcClelland** » Thu Aug 20, 2020 7:51 pm

3" inch have proven to give gains but mainly on forced induction and honestly it's obnoxiously loud on NA or supercharged setups. Turbo setups are better as the turbo muffles alot of sound.
On my 3" I added an extra silencer, I had 2 plus the back box and then a sports cat to reduce noise and even an exhaust bung but nothing helped. Soo boomy.

I changed to an invidia 2.75" with decat and it's quiet when needed but same performance.

2.5" custom exhausts are perfect on mild na setups.

ATR84 · Post by **ATR84** » Thu Aug 20, 2020 8:22 pm

Cheers @RattyMcClelland very useful. The 3 inch does sound far too loud, and I like it loud.

Post by **newkid** » Fri Aug 21, 2020 2:28 am

Mugen has its own downpipe. Absolutely no point in switching from what you have unless your planning on getting it tuned. Types means tune fail.

ATR84 · Post by **ATR84** » Fri Aug 21, 2020 6:37 am

newkid wrote: ↑
Fri Aug 21, 2020 2:28 am
Mugen has its own downpipe. Absolutely no point in switching from what you have unless your planning on getting it tuned. Types means tune fail.

I think the baffles in the skunk2 are on their way out hence part of the reason I am considering going custom. You can tune with a piggy back and I have been considering an Apexi Neo just to get the most out of the mods I do have, just don't want it to screw anything up