I have a 2005 titan with the big tow package stock size tires and the best mileage I can get is 11.2 combined city and highway I feel that I should be getting better than match if anyone has had a similar issue and found the problem and the solution I have put new spark plugs and new O2 sensors and recently put headers and b pipes and up rev tuned The truck runs very great but feel that it will put me in the poorhouse before too long any input would be greatly appreciated