I have read mixed reviews on the Holley Sniper, but after having the system installed on the 440 in my 72, I love it. I had the matching electronic ignition system installed too. Incredibly smooth and amazing throttle response. I can't speak to the difficulty of the install, but the shop that did it had it done in about 4 hours. I had to get a dropped air cleaner base for clearance. A better sized top and filter are on order.. The only downside is the external inline fuel pump is very loud. Next upgrade will be a new tank with built in fuel pump. But if you are considering the Sniper, so far I'd totally recommend it.