I went to a company called Top Gear in Aylesbury UK), agent for powerflow exhausts
A lot of people have slated powerflow on the 'net, in fact my experience with a V6 Omega exhaust fitted at another location put me off somewhat, as it was way too loud
Anyway, they were a top bunch and did a good job
I wasnt looking for any performance gains or the like, just a subtle improvement on the exhaust sound