A supercharger kit would only be like $12k for this. The engine is already bored out, that's half of the battle. For the same price as a GT3RS you could get this with an insane amount more power. You wouldn't have the traction and amazing weight balance, but if you are the better driver, you would have it hands down once you take the straights in account.
2008 E90 M3 - 6MT - AA Gen 2 Level 3
1991 Hot Girlfriend