I installed a Raymarine below deck autohelm which is in the Mainsheet, and may also be on this site. Someone else wrote a similar story after mine, but I dont recall if he addressed the issue of limiting rudder  excursion.
 I have a Mk1 1987 and needed to install blocks to limit rudder movement to prevent over extending the ram in either direction. Since I did the installation before the boat hit the water with me as the owner, I will never know what Im missing, if much at all.
  Look up by my name or the boat name

I had the same on mine. I lost that extreme rudder angle that enabled me to pivot the boat in almost it's own length.

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I wrote the most recent article in the Mainsheet and yes my EV200 did limit turning by ~ 10 degrees.  It is a balance of torque vs stroke.  I haven't missed the extra steering

Les

Hi,
I have ia B&G autopilot with an hidraulic ram below deck, and yes since the installation, the radius is reduced. This happens with all autopilot with Rams.  It is very important to ensure that piston movement is limited by the rudder end-stops and not by the Ram end- stops. 
imhave added additional parts, laminated to the hull in order to limit the rudder before the piston arrived to its end.

Best regards!