I bought a 02 wrx with a 3" turbo back 4"downpipe with sti injectors with cob intake and vf39 about 3 months ago and it ran alright.. it was a little rich.. has a u tech that is not tuned from what I can tell it started knocking and the engine started rattling and it wont rev past 4500 rpm so i was wondering if anyone has any suggestions if not im probly gana do a swap for a ej257 block and heads and intake manifold i found for a good price and wanted to know if I need to get a new wiring harness and what kind of problems i would run into with the swap