For road racing, I think the breathing on the upper end may not be worth the risks. In a road race you've gotta consider the middle ranges too. A DOHC 4valve head won't really "come on" until, maybe 3k rpm. Under that it'll be a dog, like a turbo motor off the boost. Off a really slow speed corner, you may be "up against it" trying to pull an apex in a 1st gear bend. On a hi speed track, (like VIR) you'd be ok, but in the carousel at Mid-Ohio you'd fall flat. Too fast for 2nd, too slow for 3rd. My favorite "racetrack" is "The Dragon" AKA US HWY 129 through Deal's Gap NC. 318 turns in 11mi. Without low end you'd end up holding back traffic. You'd need to use an RPM switch to open & close the secondary intake tract.