I recently bought a 89 trans-am with the 5.7 roller L-98 engine. but it is missing the complete Tune Port System. I would like to know which is the direct replacement for it. I know that some have a map sensor or a 9 injector etc... i want install the correct model so it will not be  a pain in the butt.
Any help would be greatly appreciated.  

I do not know if you still need one of the correct tpi's for your car, but I just removed one from a 89 trans am like yours and will sell it complete in good working condition for $450.