boosted92hatch

maybe someone can answer this. i built a ls/vtec for a guy in VA. i live in PA. point being i have no way to look at what could be wrong. anyway they put it in a 92 civic. if they plug in a pr4 the engine will go to redline. but when they plug in the p28 thats been chipped for dohc and also a p72 that the knock sensor has been disabled on the car will only go to 3500 rpms. now they did tell me they didnt wire up the vtec oil switch or the 4 wire o2 sensor yet. anyone know what will stop it from reving out. just trying to find some info for a freind that dont know ****. thanks anyone for some help