I posted my mods on my e46 328i some time ago, here it is again:
Cams reground to 254/254
M54B30 Intake manifold with adapter plate I got lazer cut to fit the original 328 Throttle body
Headers with no Cats but standard exhaust.
K&N Air Filter in standard Air Filter Box
Unichip and dyno tune
Rear Wheel KW at High Altitude Went From 112 to 128.5 (About 15%)
It made less power under 3000, 3000-3800 quit a lot more power then it dips as with the 330! but even a bit more making the same at 4000. After 4500 it is much better than before.
I can attach the dyno figures, how do I do that. its in xls format
I will test the manifold pressure soon to find out if there is any restrcition in the intake system.
Im considerig going to a freeflow exhaust, but are not sure if the power gains will justify the noise factor
I have got Autocad drawings of the adaptor plate if you are interested