should i go with cpi"silenced or shearer silenced, motor is 4 mil 421cub pretty much stock porting, just a little clean up port done, 20cc domes from fast, 39 pwks with billet bowls,and pod filter, +4 timing going to +7 , override straight cut gears, comp is 185 each side, what out of frames do you think i would benefit the most from? me and bike weigh total around 600, do mostly dragging 1/4 and 1/8 mile. or if there is another kind of exhaust that i should look into , as long as it is silenced.