If it were simple, it wouldn't cost $5000+. It would involve custom porting and different valves - a lot of machine work. BMW doesn't leave a lot of power 'on the bench' in their engines like most American engine designs, so slapping on a set of headers or changing an intake manifold on a 'strangled' head makes almost no difference. Without the extensive head work, the biggest power differences will come from performance chips and cams. If you want specific guidance, I would suggest you contact T.C. Kline and/or Steve Dinan and be prepared to start paying from the get-go. Neither one of them is likely to spend a bunch of time telling you how to do it when they get paid to do it.
Considering I got it @ Gateway Tech 11 years ago and can't possibly remember, I'm guessing the 'then' price was somewhere between $100 & $250, but I think it was closer to $100... maybe!
For the time being, I haven't done any driveline mods except have the clutch and a bunch of old gaskets replaced. Now my clutch pedal isn't a thighmaster anymore and the take-up point isn't on the floor (making shifting significantly quicker and much more pleasurable). Plus, I had them swap out some exhaust gaskets (which was probably never done before on the car), and, call me crazy, but the exhaust sounds throatier and there's a little more get up and go when I let her stretch her legs. What a wonderful feeling
