Keep in mind though, wehn you are running nitrous, compresion ratio goes threw the roof, somtimes with the a major amount of nitrous and severe lift (even though piston to valve clearance is not enough for pistons to meet valves) the compresion combined with the higher force from the vavle springs (they are comressed more with higher lift therefore exibit more force on the vavle) is enough to bend factory valves. This is the reason why we cannot run more than a 75 shot without upgraded valves. With upgraded valves and a stock bottom end the beta and beta 2 will hold a 100 shot. Also for this reason I do not reccomend chaging out factory valve springs. If you were to put a higher rate spring ith the valves that ill put even more pressure on the valve, causing them to bend. Unless of course you have changed compression with a head gasket or pistons. Or you got with the ferra titanium valves. Those will servive anything you can give them, high compression with major nitrous and a stiff as [email protected]#* valve springs with a severe lift cam.