I took an 850 demon off of a 500 big block stroker it was just too big. I put on an 850 quickfuel DP and it drove so much better. Demons are for WOT only IMO. Demons=JUNK....pure junk. Never had one that drove well. They are jetted bigger due to their bigger boosters. I will run a holley, quickfuel or proform over a demon every day of the week.
Again just my opinion.