Originally Posted by BMWM.D.
I've actually been considering doing this as well since I happen to have an extra driver's side "is" muffler sitting around. Would just need to buy a passenger side muffler.
Is your car an E90? If so, then it probably won't fit or sound like a 335is. Whether your car is XDrive or not shouldn't matter, but the exhaust tips are usually longer on E92 Coupes . So you might need to cut down the pipes before the tips so it looks right.
Other than that, the E90 sedans have a resonator that makes them quieter than the E92/E93, which have an X-pipe instead. To get a true 335is sound, you'd need to remove the E90 resonator and install an X-pipe in it's place. If you've ever compared the exhaust sound of a regular 335i coupe and sedan, that's the reason the coupe's are always louder.
If you try it out let us know. I would have done it already, but I hate the "sleeve" clamps BMW provides to swap mufflers. I would have my exhaust guy weld them in for me for a factory look and fit. That's just me, though.
Agreed, the clamps thing for me is something that I would tend to worry about. Having it welded like a factory OEM part would be my thinking as well.