I been running an SCT and custom tunes for about a year on my F-350 work truck with a service bed. It weighs about 10,000lbs as it sits. I been running street tunes most of time.Mileage is better,fun to drive, easier to drive in traffic.Most of the head bolt issues are from the plugged oil coolers, unless you run hot tunes and bigger turbos, injectors, ect.I'm 54 yrs old so that works in my favor, I tend to run a little slower now, lol.I'm leaving on a 3,000 mile tripe Friday and will be pulling a 6,000lb trailer for 1/2 of that.I'll let ya know how I do! While towing I intend to run "tow tunes" other wise I'll run "street tunes" for better mileage.Arizona to Montana to South Dak to Kansas to New mex to Az. Should be a fair test.