I average 16.5 MPG in the hills where I live and 17.5 out on the highway at 60-65 MPH. I wouldn't expect your mileage to be much better than what your seeing at 75-80 MPH. Your R's are way up there and as a result your mileage, in a word, sucks <img src="/forums/images/graemlins/butwiggle.gif" alt="" />. If you spend a lot of $$ on mods and still go 75-80 I would expect you might get as much as 1-4 MPG more and maybe worse mileage depending on the mods <img src="/forums/images/graemlins/shiner.gif" alt="" />. You will have more power though <img src="/forums/images/graemlins/evil.gif" alt="" />. Personally, I wouldn't have very high expectations for the ability to increase your mileage by very much. Have a Toyota 4X4, pre Tacoma, and you can expect high teens to low twenties downhill with a tailwind.

Toyo Master <img src="/forums/images/graemlins/cheers.gif" alt="" />