Just bought a 16 WRX with aftermarket intercooler, cold air intake, cobb blowoff valve, and grim speed boost controller. Everything else was either changed back to stock before I bought it or was already stock. Had what I thought was a boost leak making it sputter at around 22lbs of boost everytime. Used a boost leak tester, found one leak but didnt help the sputter. Bought a cobb accessport, since the last owner probably kept his, and tried new maps but that sputter was still there. Bought a cobb boost controller since the one it came with was grim speed and everything else was cobb I was hoping that was the issue but I just put that in and that damn sputter is still there. I'm a mechanic myself but turbos, especially newer turbos with all the electronics, are not my area of expertise. Can someone help me out here or at least point me in the right direction. I've thrown enough money at this issue I really dont want to buy another part just to have this fricken sputter still there.