Ok...well I am reading Total BMW magazine and they state that the 24-valve six used the 2-litre inlet manifold thus restricting power and explaining 20 bhp less than the 325(reffering to 323i).

So they suggest fitting a 325i or 525i inlet manifold and throttle body in the 323i for 10bhp. :buttrock
So a few questions are is this expensive and can it be done??? :help also they just threw the throttle body on there at the end. I know or believe that dinan or tecknic makes a throttle body for the 323i my question however is would replacing just the inlet manifold work?? thanks

I think that you're referring to the much talked about M50 manifold swap. It has killer air flow and with a kit can nicely replace the lower flowing stock manifold. The problem is, if you have an E46, then you probably have the M52TU engine which (I think) isn't compatible with the M50 manifold.

The earlier M52s CAN use them and gain the said 10 HP up top while losing a little bit down low.

As for cost, they are cheap. $150-200 should get you a used M50 manifold, $50+ for the mounting kit, and several hours of PITA install.

If I COULD do it, I certainly would, but to my knowledge, my engine is not compatible either.

Well I figured I was missing something since I havent heard much about it on e46's. :mad: Thanks for the info.

http://www.m3motorwerks.com/products/description.php/II=221/PA=0

With the above kit would it be possible to use the M50 manifold on my 1999 323i? I'm very interested in doing some performance enhancers and the M50 manifold looks like a great first step for me.

I've been searching around but I only found info about M50 swaps on forced induction M3s :stickoutt