Got my 120 Ultimate last week from Chief Aircraft. I have some questions on servo selection. I am thinking about JR 517's on each aileron, a JR 8411 on the rudder, a JR 4721 on the rudder,and either another 517 or a Hitec HS 81 on the throttle. It said in the manual that the 40oz servos were enough in the wing I'm just wondering about anyone else that may have used this set up? I am planning on using a YS 120 AC with a APC 16-8 prop and a Dave Brown 3.5 Ultimate Vortec Spinner. What kind of exhaust set-up is everyone using? I thought about ordering a Slimline pitts muffler to keep it in the cowl but I am also thinking about the new YS Performance adjustable pipes muffler. Any sugestions are appreciated Thanks grind!

I'm also building 1, but i'm going to use a ys 120sc almost the same thing. I think the slimline muffler will hang out of the cowl. Right now I'm planning on using the ys stock exhaust

Which servos are you going to use where and what does a stock YS exhaust look like? I got this engine used and all it had was a straight pipe. I really don't want to chop up the cowl but it looks like I may have to. Keep me posted.

i am running jr 537 45 oz on the ailerons 8101 elevator 90 oz and 8411 on the rudder. right now i am running a os 160, but i can also comment on having had a rcs 1.4 gasser in there along with a satio 180.

I used Hitec 225MG on each aileron, 625MG on elevator, and 645MG on rudder, wih a HS81 for throttle. No problems at all with that setup....

I have a 140L in mine. I used standard airtronics in the wing and throttle, FMA S350 MG servos for the rudder and the elevator,
the servos are coreless and high torque. They are really faster than you have to have.
I have one small slot under the cowl for the exhaust, I put a header on it, you can't beat the sound.
Electropiep

To see what the different exhausts look like go to Tower hobbies web site and type in YS in the search box. They show a pic of the Slimline and YS exhaust systems.
The best of the best servos to use on this Ultimate is Hitec 945 on the rudder, 925 on the elevator, 545 on the ailerons. I have 2 friends that work at Hitec. One a tech and the other is a sales rep and They say the the 900 series are the best servos they make and that they would not recommend 225's in the wings at all at a min. they would put 545's. This plane is a 3Dn machine and it is a lot of money in the air to go cheap on servos. 225 mg or not isn't designed for that. The gears are much smaller so you have less surface area where the gears touch then on a standard servo. Plus the 545 and 900's have 5 pole motors so they center really good.
This is just my 2 cents take or leave it. You may never have a servo go bad, but I hear the stories from those guys all the time about people that install 225's and other servos not designed to be installed on some of these larger over powered planes for 3d and lose control do to flutter or just strip.

DP Ulti. almost finished. Blue version looks awesome. I am using JR 531's X 4 for wings and JR 4721 for rudder and elevator, HS 81 for throttle. Have not got a final weight yet. Hope to be in the 12 LBS range. Went with my modified hopped up G-23 Glow 1.4. I got the weight down to 33 oz from 38 oz.