76th person
Hi Boltos - a pic would probably help get a response, so we know (can picture) what you want to do.
I presume the cans/pipes are to suit the stock exhaust position, so you can keep the original brackets that mount to the frame.
Do the Staintunes have mounting holes?
If not, and in the absence of a pic, I would go out and buy some aluminium strap/bar then bend it to suit the 4" round then drill a hole to line up with the bracket hole.
Richard