I had Gary build me a set of sniper oofs for my buddys 421 cub that was built by clown racing but then he ported it more hisself. Anyways on a 500ft track the best he could get with cpi big bores was a 6.5 @ 86-87mph.Now this is a stock heavy chassi with no drag chassi parts at all. I ran it 4 weeks ago with the sniper pipes, The best I ran was a 6.3@86mph with a slipping clutch and Im around 70 pounds more then him. Well he fixed the clutch for this race this week, He ran his bike this week and when I grabbed the one slip I was in shock lol, He turned a 6.098@88mph.. So I must say the sniper pipes do work very well.