Expo is also about servo arm to horn geometry. I am 5/8" out on arm and 1" off of hinge line. This allows for 80% ATV for the 5/8" elevator throw in either direction, roughly. I did not use the stock horn and used BVM c/f ones. I only use 25 digits of expo and that is for control stick interaction. I'm also a 3D flier and generally never like to use over 50 digts. In some of my non jets foamies stuff, I've actualy preffer to use servo speed instead of high expo. Servos get kind of flaky IMHO using 80% digits of expo.

I am confident that some jets get a bad rap from c/g problems, ( I learned on a KAngaroo and NOT once KANGA ROOEd it, still in pristine condition, I have KANGA rooed the KingCat prior to spoilerons) I did not add one ounce of weight to my Viper, However I did use GP3300 NMH for ECU pack. I also had to create my own custom C/F mounting of all the goodies. The fuel pump is in the point of the nose with all 3 battery packs as well. Basically from the tip of the nose (which I made removable) to 15" back is all the goodies minus control servos. heres the list:

Pump
(2) 1400 Ncd
(1) 3300 NMh
ECU
AMT ASU plug
AMT ECU
Jr 10X RX
Powerbox
BVM soft brake and Hitec MG85 servo
Robart Retract valve and Hitec MG 85 servo
JR DS 3421 nose wheel steering.

As for control servos I used the DS3421 on all surfaces, with JR 4721 on flaps.

I used Tamjets thin profile composite servo mounts glued to skins (not hatches) then I boxed them in to opposite side skins with c/f. this way they are locked in to both side skins. My rudder does not have any special considerations other than this mounting style, as it is a MKII kit.

Having burned 7 gallons of kero at Kentucky Jets this past weekend I am extremely pleased with this model and actually like flying it more than the Kingcat for now as the KC never came out of the trailer. The totally enclosed bypass is really putting out the thrust on the pegasus SP.

I encourage all to make some c/g plates out of 1/4" plywood sandwiched between wings. drill two large holes to pickup the spars, then about 2" above wing you drill a small hole that represents c/g position, then string it up in the air by the c/g hole in plates. I wish ALL manufactures could laser cut these c/g lifting plates and supply in kits, they would get far less abuse for the cost of the plywood. these heavy jets theres just no other way IMHO.

PS if someone would like to borrow my Stainless ones, I'd be happy to send them your way.

I will be getting the Eagle tree back this week so we'll see what it's got.