Hi guys like I've post some times ago I've tried to fit a chambered muffler on my Mini R52, and the result has been surprising. I've just installed OBX header and an high-flow magnaflow sports cat, an itg air panel filter with a modified airbox (it sucks the air from the front scoop with a 70mm tube and the resonator has been cut out), so next step will be re-tune it with software. But for now, rather than the stock car, the increase of power is evident. Before tried to put on the Turbo Xl I had a straight through silencer, an UK one Blueflame, well too loud for my ears....now there's a nice deep tone that screams when you pull the gas throttle...
I suggest this mod for those who like to "experiment" and who has some experience on diy, and due to the low cost of the exhaust and for the material required, it can give much more satisfaction than install another very expensive cat-back.

Price is 40 euro for the cat back, 15 euro (its a rape!!) for perforated tube, some rockwool (I reused an almost new rockwool from a stok cooper silencer) then there's only manual works (cutting principally) and welding operations (thanks to my friend Antonio)...
dremel will help a lot..
The muffler I took had the inlet of 2.25 but I wrong, its better to take the 2" type, so I had to put inside the inlet and outlet a tube that reduce the diameter and weld it until the end of the first chamber (so do it on the 2 side of the muffler that is totally reversable). Gases have to follow a path and noise will be break. I've tried to modify the Turbo XL like the Dynomax Turbo that has a sort of S inside, and its packed with absorption material, so it would be interesting to see how this one could run. The magnaflow is an empty can but the dimension are perfect to fit in the same place of the old stock silencer. Save in weight and the small dimension of the muffler should reduce also backpressure...
But I repeat, its just an experiment and I should see the results at the dyno...a fine remap would help a lot!

Here's a little guide of sequential pictures I made on how I've modified the muffler, and a video (but the sound doesn't seems good recorder so I'll try with another camera!), hope you enjoy!!!

Step by step pictures:

http://img697.imageshack.us/g/cimg3293.jpg/

Video:

http://www.youtube.com/watch?v=bbtFxPvbjno



Take all this like pure fun, I don't want to teach nothing to anyone!!!
sorry for my english guys!!
greetings from Italy!