Porting and polishing an m20 exhaust manifold?

[Thomas_Young]

Hi my fellow zoners

I've been research into porting and polishing my exhaust manifold and was wondering if any of you had tips or links. I'd buy an aftermarket header, but funds are limited(fulltime student). By porting and polishing the manifold it should release some horses right?

Any info would be greatly appreciated.
Thanks

[Silverfang]

Depends on the engine. Have heard the 325 seperate manifolds flow better than the log style one, but does mean a swap to a full 3 piece system.

Besdies that, I doubt polishing a stock manifold would gain any real performance.
If you've got an M20, a very worthwhile mod is checking Speedtouch's thread for prices, very good chip and does genuinely free up a few bhp and ft/lb of torque from the M20

[Thomas_Young]

Thanks for the advice Silverfang

Ironically I bought the "Wild" chip from speedtouch on Thursday already. The only drawback is I live in South Africa so the shipping will take another week to get here. Believe me when I say I'm like a child the night before xmas

I have the log style manifold for my 320i (2.2L bored out), but I also have a homemade branch that is 3 pipes into 1 that needs some work as 2 of the pipes are dented badly.

Maybe I should get cossy with a grinder and my TIG welding again