Hi eric, welcome to the forum, there is an RS4 forum and a A4/S4 forum (B5 chassis) which will answer most of your questions in detail. But briefly, I think the RS4 wasn't sold in the states, it was only available in Avant(estate)form only and based on the S4 with wider body, deeper spoilers and the same 2.7 bi-turbo engine with bigger turbos, intercoolers giving 380bhp in standard trim IIRC.