Originally Posted by anthony955
You're not going to get 100hp out of a tune on the 335. The 335 has no less than 350bhp for the 335i and 370bhp for the 335is (dyno proven by reviewers, shops, etc). Also from what I've read you're not going to get close to 400whp in a 335 without upgrading the turbos. You can safely achieve that with a turbo kit on the M3 running very low boost (4-5psi). So modding costs wont be too different and certainly wont be enough to justify paying $7-10 more for the 335.
The 335 is a great car, but it'll be a couple of years before I'd take one over a E46 M3.
OK here is a little lesson.
2011+ 335i has a single Turbo which produces 300hp. The ones before made 320 HP. They have the same engine as the new 335is or m1. You can get 400whp+ without changing turbos.