Earlier this week I went down to Active Autowerkes. They have a great shop with all the works, on my visit they were in the middle of dynoing a supercharged Stage II M3 (Ryan correct me if I'm wrong). On this visit I received sponsorship and had their 135i exhaust installed.
My first impression of the exhaust is that it is built solidly, near perfect welds, smooth curves, and of course it has a nicely polished surface. Lifting it you can easily tell it was a very light part. Later, when the stock exhaust muffler was taken off I definitely noticed how much lighter it was and how less bulky it is compared to the huge canister that of the OE.
I had the exhaust installed by the guys at Active Autowerkes, while doing that, Mr. Hugh was taking pictures for their new install guides. Installation didn't take long at all. The included adjustable mounting brackets guarantee the perfect positioning of the tips. I'm sure Ryan @AA could shed more light on the installation, and maybe supply the pictures.
Upon completion installation and cold start, you could definitely notice a louder idle; deep, very slight throaty note. Inside the cabin isn't as quiet anymore, you can hear and feel the low roar of the exhaust. In general it isn't too loud of an axle-back exhaust.
While driving, it is louder but not obnoxious. I don't think your neighbors will complain too much. In slow speed, low RPM driving, between 1.5k and 3k, there is the low growl and rumble, with the occasional backfire. Then coming up into higher RPM the exhaust seems to be fighting with the screams of the engine. Yet if you try to tune out the engine could hear the higher rate and note of the exhaust.
As far as performance, there much of a difference for it is only an axle-back. If anyone out there installs this with an aftermarket tune, I am sure this will help make the flow of the exhaust much smoother.
This exhaust is worth buying, after just two days and speeding ticket, I enjoy every minute in my 1er, well that is after the longer starts in cold weather (HPFP fail!).
Heres a quick video I made today, this isnt exactly a cold start, I did warm it up for a few minutes, drove it around the block. Rev progression at 7k at the highest on the last rev. Only current modifications are Forge Diverter Valves. I also think Ryan@AA can also share another video of a drive-away that they made in front of their shop.
[u2b]<object width="560" height="340"><param name="movie" value="http://www.youtube.com/v/-1oFlFwAkLw&hl=en_US&fs=1&rel=0&hd=1"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/-1oFlFwAkLw&hl=en_US&fs=1&rel=0&hd=1" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="560" height="340"></embed></object>[/u2b]
Vimeo link: