[XfireZ51]

Basically, GM didn?t want to or could not develop another ECM for a limited run of units like the ZR-1. There are many similarities between the L98 programming and the LT5, although the LT5 uses Speed Density instead of MAF for some obvious reasons, ie a new MAF would have been required. Controlling the secondaries using the ECM would have required additional injector drivers, again necessitating a significantly modified or new ECM. So the injector relays are a less expensive alternative while using the primary injector as simply the ?trigger?. Then u cut the PW by 50% whenever the secondaries are engaged. Voila!