The 44 really is the only carb I have ever seen make my 500 rev this fast . My main is a 520 but it may need more . It has a 35 pilot but idles up . I called Tony at T&N and he is an awesome person that will help anyone . I would recommend anyone with a zilla to buy a big mikuni from Tony . I bought my 44 years ago from Trinity for my other zilla that is apart right now and just wanted to try it on this one and man it makes a world of difference . I will be buying a 46 mm from Tony soon . The Zilla's do not lose any power from the big carbs . I wanted to know what jetting other people are running with the 44 .