I have recently put a set of these on.
http://www.monsterparts.com/pc/DMAS4R/Exhaust/DMAS4R.htmlOverall very happy with them; sound good, and look good as well. If you want pics I can post (don't have any on me at the moment). The only 'issue' for the truly pedantic is that if you look from the top of the bike one exhaust sits a little further out then the other (and a tad lower from the back), but you really don't notice that much (I don't think the average person would notice).
Fitting wise I had no issues at all, bar my mechanical inaptitude. There is zero instructions with them, but if you look at the youtube video and have a think about it, it all comes together very easily. Overall it took me about 2 hours, but I was really just pottering around, so could have been faster. Only thing I had an issue with was the screws that hold the cans to the brackets; I had to locktite them in as they kept coming loose, but once again that is a very small thing....
Got them from Jeff @ Monsterparts, who looked after me well.