Sorry for asking such a newb question... but is there any more difference between JDM motors and USDM motors other than emissions stuff like cat's and such?

Because you know the deal, you look at the motors and there is a difference of like 10 horsepower or so. Is that all that is different?

yup. Just slightly different compressions, sometime different cams (like the later USDM ITR intake cam). Also the ECUs are a little different, gives it a little more gas throughout the fuel map. I believe that's it.

Alright, thanks.