Originally Posted by Prestone
You have to get a Diablo trinity tuner or similar, but I would highly advise against it. The top speed is limited at that speed becuase that's all the stock tires can handle.
There is a TSB to raise it to 130 mph, but only on export models with Conti tires.
Non-stock tires could easily raise the speed, but I dunno if your vehicle inspections would be able to spot this and fail you for tampering with a safety related device.
Although I love the handling of the GC in aero or sport mode, I'm of the opinion that it will do over 120, but I sure as heck won't--not even on Nevada or Montana back roads.