i need some vtec help!!!

is it possible for a different distributor then what should be on a motor will lower the rpm peak? for example, b18a LS distributor on a b18c5 type R motor? or a d15 non vtec distributor on a d16z6 vtec motor? the reason why i'm asking is because i have a d16z6 swapped into a EG cx but it only revs to 6,000 RPM where is should be reving to at least 7,500 RPM.... a buddy told me that they could have used a different distibutor then the one on the d16z6 any ideas why its not reving that high?

you have to use a vtec distributor on a vtec motor, and you also need to run it on a vtec ecu.