Here is my plan.
Simply I am going to do electric cut out valves
http://www.quicktimeperformance.com/QTEC/index.php
There is another company that makes valves that close off the muffler as the bypass is open but I do not have the link with me at work. The QTP cutout valve is the most respected that I have found.
My plan is to install the cut outs after the cats, and control the opening of the valves from the PSE switch on the dash.
Remember my car has a turbo kit on it so the lower back pressure the better (from my research the turbos lend themselves into developing all the back pressure the engine needs)
I am assuming this mod will only be a sound mod not a power mod, so if I gain any power I will be happy.
There are generic vacume bypass valves available on line but I want to have the adjustability so I did not peruse that option.
This is a mod I am going to install in January or February.
If there are any opinions or ideas let me know.
Gary