yeah the p30 is going to look for the knock sensor and if it isn't hooked up then it is going to retard timing and everything else where it is not needed, unless it is chipped, then it can be disabled.

the p28 if not chipped and everything is going to run it ok, considering they have an ok mapping on them stock, but are meant for 1 cam...
but you had stated earlier that it is chipped, so it could only come down to the tune at the moment. Check your CEL and see what code it throws and then let us know from that.