i was told by ahmed bayjoo that unless you are running a t4 the t series turbos dont need a dump valve because they dont produce much back pressure.. i fooking hate dump valves but i have to run a valve on my gt series tubo , because of the ball bearing core the shaft is very thin and vince @ universal turbos has seen compressor wheels break from there shaft.. i'm going to run 29psi so i use a tial blow off valve which sounds ok