The Turbo XS is a a really loud valve that will get alot of attention when run. Right now it is on my C900 T16. I have an adaptor on it right now but I need to get it back to a friend wo lent it to me. I got the valve used from a friend of mine and it has been a grea valve so far and will hold up to 25PSI and retails for $189 new.
This is the quote from the manufacturer web site.
Blow Off Valve Type-H-RFL:
A new larger billet aluminum body and a beefier piston ensures the valve remains smooth under the most demanding circumstances. This valve relieves compressor pressure surge caused by changing gears or backing off the throttle quickly and is designed for turbo charged engines running up to 25 psi boost.
If you need to ask this valve is too loud for you!