A local guy brought his 2011 GT500 over with 1500 miles for a pulley swap and dynotune. I tuned the car first, to see how the 11s responded. We saw a nice gain of 36RWHP and 28RWTQ. Most 10s-11s will see 20-40RWHP gain from tuning, the gains aren't as large as the 07-09s. This is due to 10-11 having knock sensors which allows a more aggressive tune from the factory. We swapped the pulley on later in the afternoon when it was getting warmer, we saw a 3-4psi increase throughout the curve and a peak TQ gain of 42RWTQ and a peak HP gain of 25RWHP. Had the conditions not gotten worse the peak HP gain would have been better. You can also see that the car is now starving for air up top, with a peak HP gain from the pulley swap of around 30-40RWHP in the 5000RPM range, it tappers off up top due to the need for a larger throttle body. We would get 10-20RWHP from a TB swap on this car. Overall we saw a 61RWHP and 70RWTQ gain from a pulley swap and custom tune. I sell this 2010-2011 upgrade package on my website: VMP Tuning - Buy Ford SCT & GM Custom Handheld Flash Tuners Performance Economy Towing: Pulley & Custom Tune Upgrade Package for 10-11 Shelby GT500 Stock look 2.59" pulley: Larger 90mm replacement idler installed below IC tubes to take up slack and improve wrap. The 2010-2011 fusebox has the IC relay and fuse built in, the rear most little relay is for the IC pump, you can install a jumper wire diagonal in it to run the IC pump while the car is on the dyno: Since you are only making quick WOT hits on the dyno, the IC system really never has a chance to fully circulate and cool. Also since the car is not moving the only airflow is provided by a fan. Jumping the IC pump and sitting a fan in the front of the car helps to keep temps stabil and prevents major heat soak from run to run.