I once calculated the weight difference between 2-1/2" and 3" and it was significant. Generally 400 hp is considered the crossovet point. If you're mostly on the street you wouldn't know the difference. (Unless you're one of those guys who likes to say mine's bigger than yours :) ) There's only so much room between shocks, gas tank and axle. Probably more important to run an X-pipe or H-pipe.