I would like to know the AFR at full throttle, because I suspect it's a bit too rich for best power.
I took mine up to max speed this weekend as well, on a long, straight, and free of traffic stretch of road, and felt that it was accelerating slower at full throttle than at part throttle. Crazy? Yes, but I'm sure I felt it clearly. Flooring it and then backing off the throttle a bit gave it a bit more acceleration, instead of decelerating as expected when easing off the throttle.
I normally drive under or at the speed limit, but whenever I hit this road I floor it just to check if it's still running strong. Up to 170kph it accelerates pretty well, after that it slows down and from 180 on you have to be patient to gain any speed. I didn't insist on driving over 160 for too long, because I had only 2.0 bar in the tires, and there were 37C outside, and i didn't want to risk overheating the tires or the engine..I lost a bit of coolant when i cleaned my TVA on Saturday and didn't top up the radiator..plus I'm using 5w30 oil which is a bit too thin for this massive heat wave that he had all summer.
But there is definitely no set speed limiter, it is just limited naturally by it's power and drag coefficient.