first, Welcome to SV ...now, you say equal to a Holley contender? wow, haven t heard that name in a long while, they were discontinued ,.. ..thats not really saying much, since the Contender was crap after 4800-5000 rpm.. if you want to make big power, that Crossfire is gonna hold you back.the runners are just to small.... many have tried but none with great success that I know of..just my opinion, not trying to rain on your parade... we have one member that knows the XFire very well, Toobroke2Retire , and he gave up and bought a Renegade replacement.. good luck, keep us informed on your progress.. others may have different view