In the end I ordered a very good used S4 system, which was infact a 3" RS4 system, so thats going back. After that faff and chasing up several S4 systems only to find they where knackered I decided to go for the Jetex.
Got it all fitted up on saturday. The fitment is good, had no trouble connecting it to my down pipe, it doesnt hit anywhere, and all seems to fit nicely. I trial fitted the rear box 3 or 4 times adjusting the two rear hangers to get the tail pipes to be a nice fit in the rear valance and they now look very at home. Im going to swap the naff U Clamps for some mikalor type band clamps for some more clearance in a few places but its not vital, and its mainly a problem as I intend to lower the car, so didint want the clamps hanging down.
The noise is good, just slightly louder than stock - still OEM sounding. All in all I'm really glad I didnt go for the S4 setup, as this seems to be brilliant.
Its a real shame that you dont get a 2.5" stainless down pipe - does any other company do one that can be bought seperately?