Has anyone done this? I had my GPS in the truck when Allen did the street tune and he tweeked the tire size to get the speed to match the GPS. There was a significant difference in values between the actual tire size and the required tire size to get the speeds to match...like .75 inches in dia. But speedo matches the GPS within about 1-1.5 mph. The speedo was about 4 mph slower than GPS. But....now I know my mileage really sucks! I used to get about 330 miles per tank and now I'm only getting about 290 and driving styles are still the same. I kind of like the little dream world I was living in.
'02 Silverado Z-71, STS Turbo @ 10psi, TRT Custom FMIC, Comp 222/218/115 cam, Patriot Gold Dual Springs, Hardened Push Rods, 60# injectors, 160 Thermo, FAL E-Fans, Nelson Harness, Yank 2600, Built Rock On VacMod 60E Transmission,Walbro 255 fuel pump, ASP Underdrive pulleys, Gibson Shorty Headers all polished up with a Nelson Street Tune
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