I have been looking at ordering one of these
http://cgi.ebay.co.uk/Porsche-Boxster986S-3-2-986-Sport-Sound-Muffler-Exhaust_W0QQitemZ290056062535QQihZ019QQcategoryZ38 786QQcmdZViewItem
Might be a different way of installing the valve in the bypass pipe. The video shows what effect the bypass has.