No matter what you do, you will need to confirm it with jetting runs and pulling the plug. If you don't want to mess with jetting you made a bad choice trading. I also don't like slipons, they dont do much and they make you go through the whole jetting nightmare for minimal gains. I would not even mess with it as a slipon. I would put your effort into getting the mid and header pipe. At this point you are in uncharted waters and jetting work is needed and it sounds like you don't want to put the work in. Also, even if you get the mid and header pipe, you cant just throw those jets in on the manual and call it a day. Michigan is at different elevation then CA and those jets that are suggested need to be verified after you make the change.