If you upgrade injectors go to at least 740's New Style, plus the old style injectors are time bombs,, I just changed a set on a 91 Z with 60K on it to the new style. You'll need your ECU socketed and a Stage III chip. Reason for the injector upgrade is that you'll be boosting higher and your 370 injectors will be maxed out. If you just upgrade to 555 and later go to larger turbos you'll have to upgrade again, so just upgrade one time with the 740's There's been great success with the stock turbos when using 2.5" intercooler piping, massive intercoolers, Z1 throttle bodies and 3" exhaust at least to the H or X pipe.
Nistune Dealer Parts www.aaa-hiperformanceauto.com ECU socketing ECU eprom upgrade