they dont do stainless in bosal book
3 inch 316 stainless bends are around £30 each to buy 4 inch are £40
flange fitting laser cut are around £60
band clamp kits for gt turbos are £120 complete on there own
so £120 for a down pipe is cheap

it cost me over £600 to make my exhaust in parts alown not including my labour which was around 30 hrs