Considering replacing the underdrive pulley on my e92 M3 to squeeze out a little more power. I realize that it's $400 for the part and another $400 for install labor. I already have the Active Autowerke sport exhaust, AA test pipes, AA stage 2 software and aFe stage 2 intake (the one that uses the factory air box). Other than the pulley upgrade is there any other mods to increase power? I'm not ready to go forced induction yet as my motor has only 35k miles.
Thoughts or any experience with the pulley upgrade?