hellcat has more hp then a viper. red eye hellcat even more, superstock and demons more yet and talk of a 1000hp special addition in the works. base hellcat will run with and probably take a viper in a straight line but it reverses if theres even a slight turn in the road. i never warmed up to vipers (other then the viper powered srt10 pickups that were very cool) they to me look like a mix of the old shelbys and the early 60s vettes that someone stretched like taffy. for the money a z06 vette is much more car in every catagory. ive beet a few vipers with my 2007 c6 zo6. it had only 505 hp but made use of it. a c7 with 650 would handly take one. dont know about the new c8 na motored z06. from what ive heard it was the fastest yet. should have kept that c6z. last real drivers vette. manual only and no electronic nannies of any kind. just a big torquey na motor in a light body with big brakes. about as close to an adult racing cart as was ever made. thing pulled down mid 11s like a hellcat but drive it 70 down the road and ive seen 30mpg. wife wanted something with a useable back seat so we sold it and bought the challenger but i dont think anyones been in the back seat in the 4 years weve had it. that said i do like this challenger and the wife loves it and said if i get something else this one stays. guess i can live with thatThe crate engines are used a lot because they are cheaper to buy them than you can often build them yourself unless you have access to free parts and do you own machining. The components are well balanced, get excellent mileage for the horse power, they are also reliable. At least that has been my experience with the Chevy LS motors and 502 crate motors. My dad has a 700 HP Hellcat. He's wanting a Viper. I asked him why and he said, "you never can have too much horse power".