Rich Hill

Hey guys,
I bought a 2013 gt/cs with flowmaster exhaust cat and CAI with original rims that come with the edition. I happened to notice that when im going 70 mph it feels like im blowing by people on the highway like its nothing. I used a speedometer app from my phone and it kept telling me i was going roughly 80mph when my speedo said 70. I thought maybe the tires were wrong but they are Original equipment. So im thinking maybe its geared in the back? If so does anyone know what gearing would make it 10mph off at that speed? I want to tune it but I would like to know all my spec to make sure i get the proper tune. Any help is greatly appreciated. Thanks.

Mike@DiabloSport

Short of doing the math to figure it out, jack up the rear end, mark the driveshaft, and have someone spin a tire a full revolution and count how many times the driveshaft spins. 3.5 rotations will be 3.55, almost 4 will be 3.73 and a little more than 4 would be a 4.10.

Any of our tuners will allow you to adjust this as needed as well.

Thanks