I'm all for a bit of tinkering and tuning to see what you can get out of a car, lots of fun to be had from modifying and updating a stock factory car.
However, I do start to get a bit worried when people go nuts on the engine side and forget about things like brakes, suspension, tyres, etc. especially on older cars like E30 where the original set up leaves a bit to be desired.
Shouldn't be an issue on an M140i, especially if you have ordered the upgraded brakes or the M-Performance brakes.