Guys Guys Guys these heads are not the X heads we have had around for the last 41 years!

Flow is better out of the box both in terms of volume and quality of the air flow. The combustion chamber is WAY better than an X head. It has genourous quench areas no funky divots and the RHS has way better swirl and wet flow characturistics. Even if the X head was ported to make as much flow as a RHS head it still will not make as much power.