RE: Looking for something Faster!
Simple,
buy a Nelson or Jett Q500 motor and put it on your Viper. You will surpass 150 mph and be closer to 160mph.
There has been quite a few SS (Short Stroke) Q500 motors (both Jett and Nelson) listed at the big auction site. Many of them are very good engines that are only being sold due to the Newer LS (Long Stroke) motors being introduced in the last year. These have been selling for the most part around $175-$200, I may even have a couple listed before spring.
I would be carefull about which ones you bid on, I've seen some very nice ones that I know have been treated kindly by well known racers, and I've seen some pretty shabby ones from people I don't know that I wouldn't touch.