went threw 2 pro comp water pumps and 2 pro comp boxes.......finally went with msd.....but the heads work fine........but now our car want turn past 6000rpm....it seem like a rev limiter come on....sometimes it want start and somtimes it runs fine but if you put a timing light it is jumping around ....went with a msd 6al box and called msd they said the boxes dont have shorts in them..... it is the distributor