Youre looking at getting a gauge from a SRT10 ACR Viper or one of the new Nissan GTR's or any exotic sports car ie lambo, aston martin, but I see complications fitting something like that into a challenger gauge cluster, but then you'd have to find a way to calibrate it as well.
It is fun. Lots of fun. I also think it will look good. Won't be many of them around. I probably will not go that fast, but I will go faster than 180MPH that is on the factory one. I believe that Grizz will run about 190 now ( I have only had Grizz to 170+). I hope to get Grizz to 200MPH in the spring. I hAVE ALWAYS LIKED A FAST CAR.