USDM is b18c1 JDM is b18c. I would recommend you running your p28 Ecu you currently have in your si. I you want the p72 USDM gs-r ecu we could trade. I have it chipped and upgraded by Erick's Racing. The complete changover must include Motormounts, Shift linkage, Axles, complete engine with tranny, manifold, distributor, and harness. You don't need the ecu