i have 2 sets of carbs for the bike..1set has 4main jet holders all the same,the other set of carbs has extra holes in the main jet holders on the middle 2 cylinders,presume to match bigger jets.and longer trumpets both sets of carbs are as far as i know standard...about to fit factory pro jet kit that why i noticed the different jet holders while cleaning...which is the right set up .or best set up..any help or advise please...