If I am correct, a stock '91 LS comes with a B18a. How much difference is there (in size and performance) in a B18c V-TECH motor. If it would even be possible to switch it out, would it be worth it? (Used kit goes for $4950 @ http://www.nippon-motors.com/Performance%20Engines.htm) Also is it possible to bore out the heads any more? (apparently it won't work because the aluminum casing or something but I just wanted to be sure)