I have a 1989 Civic Hatch Si...I am wondering what kind of upgrades can I do without having to pull the motor?? Can I change the head for a different one?? Will that give me more power... I have already done DC Sport headers, Intake and a 2 1/2" Custom Exhaust.. IF I need to do a swap I have an 1986 Acura Integra LS with the DOHC D16A1..Would that motor make a noticable difference?? Any help would be greatly appreciated!