Imo opinion I'd go with heads and gears. For the following reasons heads are easy to change you dont have to completely tear down the engine and worry about breaking it in or anything like that a cam would be nice but realistically it runs great. If you already have the cam (I think you do) maybe that could be a winter project after race season ends. A wise car guy once told me only a fool would pull and or tear down a perfectly good running engine. Those are pretty true words if you think about it Haha. I chose gears because of the same reason rear gears are a pretty straightforward easy process. Pulling a transmission is alot of work and takes a lot of time I'd rather just change gears. This is just my take and opinion i know I'm gonna get 20 red xs and 100 experts telling me how easy it is to change a transmission Haha. Also imo tho I think this winter when race season is done you should do all of the above! :D the combo of the 4 should be quite the improvement!