I had a small stainless rear box welded to my +4 4 seater as I prefer a richer sounding exhaust.
It cost me £60 from a specialist stainless exhaust garage and the silencer was the same manufacturer as the original system.
I have used Powerflow for previous Morgans and have found the welders excellent plus they have the equipment to bend and cut to your requirements.
Custom Exhausts come up on Google in your area and they show side exhausts on their website.
