they are just a factory 4 bbl. not really made for performance(i am looking for better mileage with this carb) the secondary side will have a metering plate insted of jets. i put on a conversion plate to be able to use jets for better tuning. i would say they are good carbs. you can get a rebuild kit for about $25 from summit if you plan to rebuild it. just a basic 4160 carb.