This is in response to Blue By You on T.Y. . The double down pipes have a major affect on getyting rid of the heat in the exhaust system, from header to turbo and on. As for real world feedback we have an apex with over 7500 miles on it with the first double down pipe Dave built.The header has never been cracked or has there ever been any issues with the heat. I also own a Simons front mount that has been refit with some higher quality peices from Powder Lites wich have made it more reliable and stopped the header cracking issues. Powder Lites header and double down will make a huge difference to the point of 2-4 grams per cam arm. The major seat of the pants feel is in the midrange. I will have Dyno numbers within 2 weeks to post one on a nytro powder lites turbo at 12 all the way to 20lbs boost and an apex up to 24lbs of boost both will be run with the new RB3 programmers with timing in and timing pulled, Dave has some really neat things on the board he is working on.