I bought this new a few years ago for my 2003 Tuono (which I still have) but I've returned the bike to standard with the standard tailpipe. I've include a (slightly grainy photo sorry) of my Gen 1 Tuono with the pipe fitted so you can see what it looks like.

Quite simple to fit, its held on with the original 2x connector springs to the standard mid pipe, you simply remove the standard tailpipe, by unclipping the springs, it then slides off, then slip this onto the same pipe, get the angle right, and put the springs back on. No cutting, No drilling, all very straight forward. its held on the back with a single bolt to hold the tailpipe body in place.

May fit other bikes, if you are doing something custom, I've included a photo of the pipe diameter in case thats useful.

The tailpipe is (I would say) on the loud side, it passed an MOT etc, so no issues there, sounds epic, but it is nicely loud!