I ran Predators for years...great carb!! But its basicly a "race only" carb.
They dont work all that well at part throttle/cruising and idle.
They are really meant for WOT operation.
They are easy to tune, but they are very sensitive to small changes.
Some of the traits I have found in them are that 1) they work best on single plane intakes, 2)they work even better when they have a 2" inch spacer under them, 3) they dont like dual plane intakes, but if you use them on a DP intake, you can make it work better with the aformentioned 2" inch spacer. 4) even the so-called "street" carbs dont work any better than the non-street carb....their intermediate idle circuit is only marginally fuctional, 5) they love tunnel rams and roots type blowers!!
They are very simple compared to a Holley....they dont have nearly as many passeges as Holley's do.
People dont use them because of hood clearence issues....but more importantly, they dont use them because of intimidation...the fear of the unknown....its not a Holley, so they dont bother to mess with them.
But the design has been around for decades....dating back to the old "Kendig" style carbs.
I used to have a Predator carb that I tricked out...made a couple of custom fuel curve cams that were "in between" the ones offered by Predator, plus, it had room for me to hide a nitrous injector *inside* the carb itself!!
Oh yeah, I won some money with that carb on the streets!! I had a totally hidden NOS system on the car that NOBODY ever was able to find.
They'd all shine their flashlights around the intake and carb, looking for the plate or something, but little did they know, the NOS was plumbed straight into the venturi of the carb itself!!
I should have kept that one...it worked real good.