after rippin my exhaust completely off from the downpipe back i had a systek custom built in stainless steel in sheffield. got a new cat and a cylindrical sports box and the pipe out to the back, also had a couple of skid plates made for each end of the box from exhaustsuk.com in sheffield. it wasnt really cheap but comes with a lifetime guarantee at £550.
but, it sounds the muts nuts!!! hehe