Originally Posted by CombatNinja
335is is close to the Performance Exhaust. Close enough that I wouldn't bother making the swap. One thing to consider is that the 335is is N54-powered while your 2011 335 was N55. Those always sound a bit different even with identical exhaust setups. Not to start a flame war but I think the N55s sound a bit better all things being equal.
I would agree with combatninja. I had the pe exhaust on my 135 and loved it. I was thinking of putting the pe exhaust on my 335is too, but the stock one just sounds so nice (although I don't think it's quite as loud), I can't justify the expense. plus you would lose the cool double walled black tips from the IS exhaust, unless you cut them off and put them on the pe one.