Well, first you have to understand that your actual HP/TRQ increase will depend on what your baseline HP&TRQ numbers are now
So before you modify anything on your car...go get a couple of baseline dynos done at a local shop first.
Use that same dyno once all your mods are done.
That way, you can actually see what the HP&TRQ difference is after all your aftermarket performance parts have been installed.
As for the hardware...I have a few suggestions:
If you like the Dinan pulley
, and you are set on getting a Dinan tune
...I would suggest that you get the Dinan x-pipe
If you like the Gintani rear muffler, then get that as well. (if you don't like the Dinan mufflers)
As for rear end gearing...
4.10 gear ratio is unrealistic option for the 7-speed DCT.
3.45 or 3.62 are the best two options to improve acceleration.
As for an intake on this car...
SAVE YOUR MONEY.
The factory air box on the M3 is an engineering masterpiece. Removing it to install an aftermarket option is a waste of money in my opinion.
The only thing you you need to improve the performance of the stock air box, is a good quality drop-in air filter from BMC or Macht Schnell.
Realistic HP/TRQ gains for:
*High performance air filter element for the stock air box
*Dinan 16% under drive pulley
*Dinan performance tune for the catless x-pipe
*Gintani rear muffler section
Estimated power bump: + 35whp & +25rwtrq estimate on the same Dynojet dynamometer under ideal conditions.