you'd prolly gain much more in all directions switching out to roller rockers, or even just roller-tip rockers
any 2, non-canted valve engine is pretty much undervalved...so reducing the lift & duration of the intake valve will just multiply that, plus now your potentially dropping power, which can make the engine work harder, thus using the more fuel, to move the car the same as it would with a stock ratio rocker
if you are really despirate...look here
www.hotrocker.com