ok now i hear a lot of talk on piston speed and everybody afraid of stroke ok here it is maximum piston speed piston & danger of piston speed faliure is a average of 5600 fps now using a 5.25 stroke with a stock evo 7.440 rod lenght your talking 6500 rpm & a 4.25 stroke lenght with a twincam rod lenght 7.660 average piston speed of 5600 fps is 8000 rpm a 4-3/8 stroke does not hit this untill a little better than 7700. how many people here run their street bikes this hard piston stability was a issue with a 3.5 bore with strokes larger than 4-5/8 due to shortening of skirts & pin placement to crown with a 7.440 rod but as the rod lenght increased to 7.660 it allows for .220 longer skirt min and as bore size goes up you are increasing the useable load surface verses the old shovel and evo stock bore stuff and with the twin cam motor with the piston oilers you now have oil for the skirts that was not available before & that reduces heat build up and friction which killed the old style strokers and a 4-3/8 is only .125 longer than the evo and has the same rod stroke ratio of 1.75 so angularity is not a problem. ok anybody else want to chime in this or am i just venting.:hmmm: