I own a 2002 and I plan to convert to a CIS set up... wat mods can be done to it and is it possible to get a larger throttle body for the manifold?

Depending on what mods you want to do, CIS is not worth upgrading to. A good setup from a 318i with the intake, injectors and a Megasquirt setup would be way more worth your time. CIS is alright, but for performance, you'd have to find a turbo warm up regulator and fuel distributor from a turbo audi or something of the nature to make it worth your while. CIS is better than stock carbs, but not as readily adjustable or as much adaptability to power increases. As well, the stock CIS runs lean when heavy acceleration is needed so the engine does not get enough fuel. Adding a cold air intake will make the engine sound louder, but doesn't add much power. I would suggest to use a good carb setup or go efi. There's a reason BMW went to EFI.

As far as throttle bodies are concerned, I heard that a Volvo 240 of the same vintage (80-83) will work and flow more air as a result of their larger bore. I was doing some research on this subject because I'm limited as far as cam profiles and I think with the 2.0 I can get just a little more power compared to the 1.8 with the stock throttle body. The gains were not confirmed with dyno numbers, just seat of the pants. I'll have to try it.

Cris

Thanks. I have another question, can i used a 318i throttle body on my fuel injection manifold (off an '83 320i)? Can I use the 318i efi with this manifold? Sorry if its a stupid question.. I'm still quite new to these cars.

The manifold from a 318i bolts up the same as a 320i manifold with injection. The 318i accepts EFI injectors, the 320i needs a bit of modification to accept them. You could retrofit an entire 318i systme if you had it. It would be pretty easy to do. You would need the fuel pump out of the car as well or similiar high flow pump.