what is the difference.???

 

Pretty much the big difference is that the JDM is speed limited at I believe 120 MPH, where the USDM does not have that limiter. There may be very minor differences in the feul or spark maps, but I haven't heard of them. I went with a USDM ecu on my JDM swapped H22, and with the JDM injectors it runs just dandy, actually runs cleaner and passed my emmision test better than my US H23 did.