I made 675fwhp with 2.5" piping and went 10.10@150 consistantly. 30psi all the time with a non-ball bearing turbo. Those saying 2.5" is too small for 20psi is rediculous. 20psi on a 12A or 20psi on a 42R? Crazy. The speed at which the air is traveling and arguing about 90 degree bends....most people will never come to realize the benefits of low viscocity piping and flow.