There are more than that! There are 2bbl Snipers and QJet Snipers and 4500 version Snipers. It does get confusing. For the typical big block engine I just ask a customer how much power they plan to make. Up to 600 or 650 hp you use a regular Sniper in the color you want. For more than that there is the Sniper XFlow which can go up to 800 hp on a 4150 bolt pattern. Then there is the Super Sniper if the customer wants to monitor oil pressure and fuel pressure with the Sniper.
The 4150 Sniper is a different form factor and it works better on some engines. Holley doesn't really explain this but the throttle linkage on the regular Sniper doesn't line up with factory throttle brackets. Also, on a regular Sniper the wires come out the front so they get close to the distributor on a big block. It is better to have the wires come out the back on a big block so they stay away from the spark plug wires.
