i am mainly concerned about the gas mileage as I am driving around town alot and am getting around 10mpg...also, I know that i might almost cost less to get a whole new 4runner than to buy all of the mods that it would take. My local junkyard has plenty of new 2gen 4runners that I could pull alot the right materials from but I just don't wanna have to go through all of the changes if it going to be so painful. Will the 3.4 match up with my current set up with out having to change everything under the hood?