I have looked on youtube but I have yet to be given information on where to buy and prices.
The BMW performance one looks very nice, but in Australia it is not available, it does not have it on the BMW Australia website like it has on the UK one (I've checked both).
I really am not sure, so don't let this come across as being a smart arse but I the 135i and the 130i exhaust system might be completely different and I have a feeling they are different, so they might be a mismatch. I say this because I go to websites like turnermotorsports and others and they dont even sell anything for the E87 130i only the E82 and E88 1 series coupes and converts, nothing for the E87 hatchback.
Apart from Eisenmann which is priced ridiculously and BMW performance one (which isn't available in Australia anyways) I can't find one.
I might give my local dealer a call anyways to see if they distribute it in Aus, but if its not on the website, I am fairly sure its a no go.