i have noticed i changed stuff on the motor and it runns smooth and i think the exhaust is gunna kill it tho that he put on the car the car ran like crap when i got it pretty much running open header when i go it from him but now its running great smoke a lil at peak rpm but what motor wouldnt with a open stright exhaust no cat and a exhaust leak lol but soon it gunna be getting pulled out and a built d16y8 with a z6 head will go in