http://www.spiralturbobaffles.com/ this is the link to the website that I was using. comp ratio on the engine I was using for testing was 11.62 and db's were dropped across from idle to wot. We didn't get a chance for any performance runs because the engine was going sour and it wouldn't have been a fair test. Was going to test them again this year after the fling....but you know that story....car should be back on the road in 2-3 weeks...nothing major....broken motor mount, bent rim, bent header, and brake problem....biggest decision now, is what side exhaust I want to go with....