What kind of plugs to buy?

x2 what dan said,i did a test on a 440 street car, autolite,e3 ,and splitfire.every run i changed plugs from autolite then e3 then splitfire.it ran the same 1/4 mile times not a gain in sight.the car ran 12.30 @113 every time well it went 113 every time it went 12 30 1231 1229 all aty 113.:oops: