Put it on ! I dont have a 335is but I did have the 'is' exhaust on my e90. Liked it a lot, but i missed the burble sound from my 135 AR-Berk set up. So, I installed the BMW PE and it is truly a much better sound. There is a bit of drone at 2500-3000 rpms on the hwy, but not a problem for me. I am completely happy and will not move towards the Dinan or Vanguard which I thought I would.