If you care about MPG's,.. (I sure do)... go with the 52.5...
Pilot has a big effect on mpg's...
As far a the hesitation... is your idle speed too low?...
Slight hesitation is normal... action/reaction takes a tiny second...
For a tiny fraction of time, when the throttle plate opens, you get the added air before it draws the fuel...
Normal,.. are you being too picky?...
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If you work that out completely,.. you'll be too rich the rest of the time, and yer' mpg's will suck...
Tis' the nature of carburetion...
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