i have a 93 n/a with intake/headers/exaust and i noticed a lot of popin noises when on the gas. so i had it tuned.when i read my a/f reading i was runing an average of 15.5:1 ratio which can kill a motor. i purchased an AEM fuel pressure regulater and turned that baby up to 60 psi and my fuel ratio was down to a performance 12.5:1 ratio which added 13 f.lbs of torque and 10.1 horses to the wheel!!! the best part was it was only 250 dollars and a breeze to install. plus horse all through the powerband is nice....very nice!!!!