i dont know what .26 comes stock in my Mayhem ST But I do know for a cheap motor ( like 150 or less on Ebay) that thing hauls ass... I have the mayhem pro buggy with a VZB and a Mayhem ST with a stock motor, and I cant tell u that that VZB is any faster... Sorry if im studering... must be the Captin in me I will tell u that after my 18tm I will never buy an OS motor again. Just my opinion tho. later