You have some of the best resources here in SoCal and you don't trust what we say? :-) First of all, to run the 720's (which are RC, not NISMO) you don't need to alter anything. To run the 740's (which ARE NISMO) in your '90 you need to modify the lower intake manifold and buy a 95 fuel rail. there is no modification neccessary to the fuel rail.