Ian - the Bursch exhaust was included in the spares package with my car.
It's currently fitted with megaphones:
which are
very loud - much louder than my 911R-inspired car !
I need to put a quieter exhaust on to get it through an MOT (as well as fit a handbrake !) so I am probably going to fit a std 914/6 silencer (or a 911 one) initially.