http://www.stealth316.com/2-injectortypes.htm
different style of injectors.
NAs have high-resistance injectors. TTs have low-resistance injectors. to make TT injectors work on the NA harness, you simply have to wire in some resistors. however, without increased airflow (forced induction, or nitrous oxide), upgraded injectors are a waste, and actually can cause your engine harm if not tuned properly.
as i recall, jeff, you have some head work done? before upgrading injectors, i would get a datalogger and watch your O2s at WOT. also, you can check your IDC (injector duty cycles). but most likely the stock injectors will be able to compensate for the minimal additional air provided by head work (port and polish, etc).
unless you are running upgraded cams, the stock injectors should work fine.
bottom line, get a datalogger and monitor your engine parameters to first see if you are maxing out your stock injectors. if you are, then an injector upgrade might be a good idea.