The fastest engine for a viper 500
I am looking for extreme speed with a Viper 500. I have some fast planes now but I would like some thats just crazy fast. I have done a lot of work to O.S. engines in the past like porting, polishing and nitrous. But now I would like some thing with extreme speed out of the box. What is the best one to get. What are getting for rpm with what props.
Thanks