It has been proven in wind tunnel testing that leaving your valve extenders on/ having long valves makes no difference to aero dynamics. There's too much going on for it to make any difference. The only benefit is not having to listen to them rattle if some one hasn't tightened their extenders properly, or stuck their tub on with the valve at an angle so it knocks every time it goes round.
It has been proven in wind tunnel testing that leaving your valve extenders on/ having long valves makes no difference to aero dynamics. There's too much going on for it to make any difference. The only benefit is not having to listen to them rattle if some one hasn't tightened their extenders properly, or stuck their tub on with the valve at an angle so it knocks every time it goes round.