according to BBK, on a stock 4.6 ford, an X pipe gives a DYNO PROVEN 12 to 25 hp, and 10 to15 hp from an H pipe, and 4.6L is much smaller than 400 cu in, so much for that theory. all I was trying to say is that an equalizer may not be a bad idea, and i think that its proposterous to think that thousands of people put them on their cars just to quite them down.
