i really need to get rid of an m30 engine if you are interested.
M30B35
* 3.5 liter (3430 cc) SOHC inline-6 cylinder
* 9.0:1 compression ratio
* 208 hp @ 5700 rpm
* 225 ft·lbf torque @ 4000 rpm
1. Port, polish head, new valves and springs (performance level).
2. Performance camshaft
these will give you more durability. perfect to do alongside a turbo/super charging job. i think you will be disapointed if you do them alone, looking for more power. your best bet is to chip it and be done with it, or just swap the motor. theres not alot to be done with the m20. bmw made the larger block for a reason...
3. larger throttle body and MAF (M30 type)
4. larger injectors and adj. fuel pressure regulator (is it necessary?)
honestly the money you spend would be much better spent on a new engine. night and day difference between the m20 and m30 in the e34. m30 vs m60 is like being in a different galaxy.
If you are dead set on modding your m20 start with the chip. then try a free flowing exaust, still unhappy.......then port the head. good luck
-Chris