Makes sense. The 1.60 with a perry pump is 4 oz heavier than an OS 1.40 RX
The 1.60 with the header off the side keeps some weight forward while the rear exhaust keeps weight aft.

Your servos weigh .2 oz less then what I am using. I am using the Hitec MG servos.

Sounds like the same CG when I had 4 oz on the firewall.

How do you like the way the plane handles with your CG at 180?

I felt like I was a little behind it all the time. With the extra weight on the firewall moving the CG to 160 it is a little more tame.

What class are you flying?

Carl