thanks for the reply suberdave. it is a bone stock setup with maf. I am an ase mechanic and have had a tubocharged grand national and many other hotrods. the problem is I have no experience on roos other than head gaskets, timing belts,..etc. I am looking for interchange info (use heads from a yugo because they flow better:confused: ) I dont know where the casting #s are or the diff between ea18, ej22, or upyours1st. If I had this info I could perform a better search. thats why I am looking for the basics. If someone could break down roos for me breifly I would have a better understanding of what to search for. I have found all kinds of info on lift, suspension, tranny, but no interchange. If this were a sbc I could write an interchange manual but that comes with 20 years exp.I have about 1 week of subaru experience. so if anyone can link or break it down that would be awesome:headbang: :headbang: