Was at base hobby shop today and wound up being forced to buy Super Tigre GS-40 ring. This engine has been in the case forever, and I got a pretty good deal on it. It's the older version with the non-silent muffler. Would have prefered GS-45 but this should haul the Avistar around with a little more uumph than the old LA. Should be no problem to mount, looks like exact match size wize, but is a little heavier. Was looking for some hints/suggestions from any of you that have up-engined your Avistars... and please, please don't tell me I should have gotten an FX-46, I hear that all the time at the field. S-T was a LOT less expensive! I'll post some pics as soon as I get home and get the camera out....