Oh well, i dunno about the cat, but im fitting a custom exhaust, cat back...and so far... ive spent... $45 on 2.5" and 3" piping. But this is cost price, as im doing all the labour myself. Also, im getting the bends done at my dads work, they use an oxy torch or somethin the rather, with sand or something in the pipe.. to bend it and keep the same diameter right the way thru! Dunno how mandrel bends work, but this is basically the same thing, (maybe is iunno)