I have had some good recommendations about a company called Longlife. They build bespoke systems and I have received a quote of £850 for a full system for mine. They use a very good standard of stainless steel, this being 304 grade. It is a franchised company, but if a local company goes out of business your exhaust will still be covered by another one that is the nearest to you. It will take a day to fit it as the exhaust is manufactured during that period. I have had a concern that the resonance of the new exhaust would sound tinny, but feedback that I have received has been good about this concern. DMG off the shelf system is about £810 + delivery + fitting and I cannot see on their site what grade of steel they are made of. My feedback is off the JEC site.