I'm using the stock mani but it has a very good welding job done on it and has a collector with a 38ml gate and screamer on it. I have a bleed valve ,z32 afm with big pod,oil catch tank,fmic,full 3inch exhaust, gtr injectors and reststor pack,new yellow jacket coil packs, power FC with controller plus have just scored a aftermarket clutch and lightened flywheel and am thinking of cams and if needed a oil cooler..