Originally Posted by Nish 135i M DCT
Thanks for all the responses and advice. I will definitely enquire about the software upgrade.
I was also advised to install the performance exhaust on the M3. Is this worth it? I must admit, I will miss the 135, especially the sound of the turbos.
I briefly considered that, but the general answer is that most exhausts are purely audio candy; a few of them will give some power gains, but not enough that that should be your motivating factor. Personally I think you'll be so happy with the stock sound compared to your 135i that you won't feel any immediate urge to make it "better".
But at the end of the day, I decided that I love the stock sound because it sounds like a muscle car below 4K RPM and starts channeling F1-style banshee wails above 4K all the way to redline. And the M Performance Exhaust is FAR more expensive than other solutions, so the advice about hearing an exhaust you're considering in person before pulling the trigger applies even more with that exhaust. But IMHO, there are better ways to spend that amount of cash. For me, since I'm rapidly developing a track addiction, I would sooner buy a set of dedicated track wheels and tires as well as adjustable camber plates to get a square setup with more negative camber in the front so I can reduce the built-in understeer this car has. But that's only something I feel the need for on the track; if you regularly encounter this car's understeer on public roads, you're driving way too hard for that environment. After that I would probably get a BBK. Add the fact that I'd also like to set up a projector-based home theater system and an exhaust fell very rapidly down my list of priorities.
Bottom line: Get a feel for (and enjoy!) what you have before you start thinking about ways to change it. You might be surprised how little you end up thinking needs "improvement".