If its a stock quad, there is a reducer washer in the pipe, remover it and the LT800 picks up and scoots much better !
I ended up with Tudors doing a bore, and some head mods and very light porting, with a chain and sprocket change going from a 530 pitch to a 428 and a few teeth less picks up gearing, Jeff was doing wheelies in his parking lot and he weighs in at 230lbs, wouldnt worry about an exhaust unless you get a LRD, the Trinity and CT pipes are ok but loud as hell, took the oil injector off and now premix 30 to 1 , she starts easy runs all day.
Tell you teh best money spent was on shocks, the stockers are junk, kid looks like a bobble head when riding, went with work shocks, and wider a arms and that LT80 was passing kids with larger engines all day long on the kiddy track.