Just thought .....I've a GP Balance machine somewhere ...unopened ..! But...some guy is telling me " 5.5 to 6" ..should be fine.." for the new c of g with the tank in the new pozition... hell that dont seem right ...its only 3/4 inch or so rearwards of what you guys where flying at ...With 16. 5 oz 10" + further foward ...there's got to be a correct way to calculate this .... oh... got the Du- bro hinges ....like you said ...impressive..!