JLB, the mount to spinner distance is 6 inches. Matter of fact, since the 110 and the 105 share the exact same bottom end, most of the 105's measurements apply. Major difference is the spark plugs on the 110 face back toward the rear of the engine, and the plug cap to plug cap distance is 10.5 inches.

Regarding strength, the Extreme bottom end has been in use since early spring (in the 105), and had there been problems with it, we all would have heard about it. Take the 105 and swap in the 110 cylinders and pistons, and you've got the 110 Extreme. I had zero problems with my 105, and anticipate zero problems regarding strength with my 110.

I had used the K&S cannisters for 70cc cylinders with my 105 (my first use of cannisters) and yep, I made up my own headers using parts from Desert Aircraft. I had zero problems with them either.

For my 110, I followed Kris' suggestion to use the larger Pefa LL cannisters (still a lighter combination than DA or 3W with regular mufflers) and gained 300 rpm. I again made up headers, also following Kris' testing and used simply a shorty header/90 degree elbow giving an exhaust outlet to cannister inlet length of less then 5 inches. The Pefa LL headers ARE big with a 2 3/4" diameter and 16" cannister length. The Pefa L headers have the same inlet and outlet size and the same diameter, but are only 12 1/8" in length and may solve some fit issues if you don't have room for the "bigguns". My Wild Hare Extra does have room. BTW the K&S cannisters for up to 70 cc cylinders are 2 3'8" in diameter by 9 7/8" long so are even smaller in size. I used a 10" header length per DAs suggestion. The K&S are available from DA at http://www.desertaircraft.com , and the Pefas are available from Aircraft International at http://www.aircraftinternational.com/ .

I'm not an expert, jsut learning as I go. I'm just on my second gallon through the engine, and am 400 rpm down from the 6,900+ rpm Kris reports with a similar setup using a 28x10 Mejlik prop on his well broken in 110. I know it'll get better, just takes time and learning how to do it. Even now, though, the 110 YANKS my 30 pound WH Extra out of a hover and runs skyward until it's a dot in the sky! Yeah, so far, so good.