I run a Savage RDLogic twin chamber exhaust on my Genny.

I don't think its making any more power, but it is quieter, that's the reason why I did it.

Theoretically is should be making less power as the pipe it tuned for higher revving engines, but I'd be buggered if I can notice any detrimental difference.

As for the cooling head not sealing, I get that, but it just needs the 6 head bolt tightened now and again.