c56? i think thats the one for the 20v. the 20v box has better ratios more suited to its power band. i run a c50, which was originally from a 4ac with my 100kw 4ag and first gear is shit bit of a flat spot between first and second there is a pdf floating around somewhere that gives u the ratios of teh different boxes, but i cant remember where i saw it and i had a look on this computer and i dont have it anymoer sorry maybe someone else can help.
but it shouldnt be *that* slow off the mark, clutch isnt slipping or anything is it??