i'm running the EXACT same setup (pantyhose airfilter though), but i'm only about 20 miles into the break in. at first it was terrible in the midrange, but i moved the needle to the second highest position and its very happy. it sounds like your needle is already in the right position if it pulls hard from 1/2 - 3/4 throttle. full throttle is completely controlled by the jet so you should take a ride at full throttle for as long as you can and plug chop. my guess is because i'm basically using no airfilter and my 82 jet is working out you may need a 80 or 78 like you mentioned. give it a try.