138 with plenty of motor to spare. Was trying to catch the tail-end of a Mod Day after getting home from a trip to visit my in-laws in South Carolina. I was on the phone with SD GTP (hands-free was being used), and he was egging me on. He said that people were starting to leave so doing 80 in a 65 was still too slow to get there in time, and I should open up the GXP all the way.
Next thing I know, I look at the HUD and I'm doing 135. A couple of seconds later it hit 137 and I decided that I didn't feel like being arrested and getting the car impounded after only having it for 3 weeks, so I lifted and the HUD showed 138 right as I took my foot off the pedal.