95-99 RS & GS models have the 420a in them. 95-99 GST & GSX have the 4G63 turbo motor. Now, the earlier years 90-94, they had 4G63 turbo and non turbo versions. 90-94 also had a crappy 1.8 liter motor, which if I am not mistaken was a 4G37. I could be wrong on the engine code but I am pretty sure that is right.