Mine perform spectacularly, and look.......well you know......eye poppin good.
Im running holley 590's,(4160's vaccuum secondaries) progressive linkage, jetted with #62.
setting up idle circuit is critical to good idle (not loading up) and performance,
if you are going to run 650's I would definately run vaccuum secondaries and a progressive linkage , 1300'cfm all at once will throw any engine on its face.
KK