I bought a 2008 V8 I am avg 12 miles a gallon which seems low a lot of other V8 owners are claiming 14-18 MPG. I run 91 octane and have dual exhaust from cat back which I thought would help? so I am wondering is it a timing belt issues? Has anyone ever put in aftermarket air intakes or ECU flashes?? I would love to know what's working for others and aftermarket companies.