From what I've read when others have done flow tests on heads and intakes, they say that port matching on gains like 2% or there about a. Of course all are different and if it was real mismatched before and clean through after you might get a little more but really in the end it's not worth the trouble. Your best bang for the buck is said to be a bowl blend. Good for up tp 15% IIRC. Even that is not going to make a big difference on a stockish motor.