***I would try to move the radio installation as far forward as possible in order to reduce the amount of ballast that is needed, if you haven't done so already.
Yeah, the battery is mounted at the firewall below the fuel tank.The radio is just behind the tank.
***I agree that a data base is useful. Have you looked at the Tach Readings forum on RCU?
I didn't know there was such a forum. Thanks Artisan, I'll take a look.
However, my P51 Mustang with TT91FS and no muffler sure sounds nice on a full-throttle fly-past at about 12,500 RPMs.
XJet, Will all 4S engines run well without tank pressure from a muffler? I really don't like the look of the muffler hanging out the side of my Zero and noise is not an issue where I fly.