For the 800's that had carbs.
I would add v force reeds, check piston tolerances, advance timing to 1 to 2 degrees, seal airbox and add intake kits, clutch and gear.
For the cfi4, 800's it needs the Pcv map bad for the lean spot which some called hesitation back then. Without a Pcv it's not going to run right.seal airbox,intake kits, check piston tolerances,clutch and gear.
For the cfi2 800's(2011-now) with very mild port timing. Put in cat pistons,shim,(Terra Alps), trail port cylinder, check tolerances.use a Pcv, advance timing, seal air box, intake kits, leave stock exhaust on as it was that good.,clutch and gear.
For the 800 ho.
Pcv with timing, intake kits, a good pipe,clutch and gear.
I'm missing a lot of mods but this is just general.
