you want the OS 18 cv-rx with the slide carb, if you are having problems with pull starters you are doing something wrong, get the OS with the pull start, if you cant start an OS with a pull start you arent meant for RC's, my OS always started for me, and no charging batteries, if you are using a starter box you want a non-pull start flywheel, hpi makes them, also you want some different engine mounts to lower the engine and allow it to contact the starter box wheel, the ths racing exhaust system is a fairly cheap and cost effective exhaust system, i prefer the rd logics turbo II pipe though, little bit more power, and use the heat cycle method for your engines break in