It’s actually not that much difference without exhaust onWhatever you do...don't be without a silencer.. you'll get fed up of the racket.
I used to be chief engineer at a company called Prodrive driving and developing prototype cars there.Why pay someone to make one, just go down to your local milking machine shop, grab some stainless pipe (and a couple of bends if needed) and make your own. TIG or MIG will stick it all together.
A $5 tube of metal polish will make it shiny if thats your thing.