Thats what I have heard about the Dual carbs, Being better then the stock PICT, and like you I was going 65 tops when I got 35, On the journey home I did about 70-75 and I got 21mpg. I have no idea what has been done to my motor though. It was "rebuilt" five years ago and my parents didn't ask what had been done but so far I have found the heads are Gasket ported and it has the earlier 3 bolt cam gear on it (not fun to find out when you ordered a oil pump/filter that took a week to ship) and I believe it is a 1600CC motor.