when it comes to 3-4 rotors, you would want to run the non rx8 housings and irons, also the E-shaft is not something you want to go "cheap" on as suggested i think you should highly consider visiting defined and talking to Logan as he has actually built a 4 rotor. he knows the right steps and the cost estimate that it will run to make one. for example a proper 20B build and install with all the supporting mods is anywhere from 15-25K