Not sure how well the O-rings will stand up to the higher exhaust gas temps in a gas application. They don't last very long on that header when running glow, and I suspect you might be changing them very frequently when running gas. However, if you replace them with Viton O-rings it might work out.
One other thing about the OS header - if I remember right, it's got a fairly restrictive opening to it. Might not work as well as the Macs header in the SAP-180 application.
Ed, that was my thinking as well concerning the O-rings. Just sounds like something that wouldn't last long with a gasser.
I didn't know about the smaller opening... also not good.
Sent my registration info to Rick W for the Jackson event. Hope to see you and Matt there.