1) GM top brass wanted to restict the HP ratings for both cars to 10 Lbs./HP. Since the Firebird was a lighter car, the HP was reduced to 325.
2) To achieve said difference, Pontiac modified the linkage between the primary and secondary throtle shafts. The secondaries were not supposed to fully open.
The carbs were not actually the same from the factory.
Now ... in reality, both HP ratings were misleading, just like the RA IV HP rating of 345/370 HP.
