We are running a WIX racing air filter with a K&N top. Works well. It's only a 3" filter. Anything taller blocks my vision. The engine makes approximately 800 hp The car has been 8.70's @ 155 That is with a mechanical throttle stop at the pedal turned out so we are only getting about 3/4 throttle.
I dont think the filter is restricting anything. I am sure the car would be in the 8.50's at WOT