pipe temp
the hotter your expansion chamber / pipe the higher rpm your max hp will be
so why not go cold pipe lower rpm max hp ? because to clutch a sled you need to know where max hp rpm is the most/ the most often, with bare pipes that elusive sweet spot can wonder all over the 7-8000 rpm range as cold pipes get hot, then get cold with 50mph 15 degree air zinging through the hood on the trail, then hotpipes while winding through the trees then cold pipe while you size up your line up the hill, then hot pipe again 1/2 way up your hill climb etc etc etc.
so you can make a hot pipe and keep it pretty hot and consistent with insulation, and keep it more consistent with thicker steel construction of your pipes with insulation.
the other side benefit of the insulation is sending more of the heat of your motor on down the hot exhuast pipe and evacuating the underhood area of heat that is detrimental to having a good cold air supply and cooler non deto motor.
so when you buy a thin skin aftermarket pipe and don't cover it, expect to chase clutching around some and find the sweet spot in the power band now and then. ceramic coating can help some, won't help much though when a cloud of cold fine 10 degree snow blows in the hood area onto that hot shiney pipe just when you want to stab the throttle for full power . big azz thin skin twin pipes on our old peaky hp sleds , you chase sweet spot clutching hourly. The new wider torque curve 800/1000 cc motors.......... most riders may not even notice that much variation in power delivery.......but the careful observant tuners will.