I had the bmw m performance exhuast fitted on mine on Monday as a little present from Santa. It provides the much needed sound track the 125i needed. Theres a real nice bassy drone sound on acceleration which is especially noticeable between 2-3k in sport mode. It's nothing in your face though which suits me just fine. Noticed a few burps and gargles also in the limited time I have driven on it. Can't wait for the summer now to open up that sunroof.
The car feels pretty much complete now which is the best compliment I can pay the exhaust. I didn't expect to so pleased with it.
On topic I can see myself back in a Golf at some point. Looking forward to seeing how the mk7 R turns out.