I've never raced a 4.2 vs. the TRC motors, but the 4.2 is a good motor for me. But I've heard that the TRC motors have exellent torque without a large trade-off in speed. All three (4.2, R-Spec II, and Formula 34) are great motors. No the 4.2 doesn't need an FET mod to run, but I'd consider getting one done to your car. If you send it
here then you can have it done for you. The FET mod is just as good as an Internal dual cell exept it is lighter so you would actually have better acceleration. Another major plus is that it looks almost completely stock, whereas a internal dual cell would require you to flip the PCB board over.