adding trim line to part changes total length

I am using Solidworks 2010.

I have created a weldment of a bent part.  I use the weldment feature to get the total length automatically.  Using a sweep means that I have  to do additional work to get the total length.

In this case, the form is 3/4 of a rectangle.  At one end, the customer end point is right next to the end of a bend segment.  I need to have extra material  for the bender to grip the tube.  That's easy enough. 

Next, I need to create a trim line for the shop to cut after bending.  Normally I create a plane where I want the line, sketch a circle that encloses the part I want the line on and make a planar surface.  Then I use the planar surface to make a split line.

On my last part, the total lenght in weldment properties is listed as 154 11/16".  The sum of the dimensions added manually is 163 3/8".

If the roll-bar bar is moved above the split line and surface plane features, the total length in the weldment properties is listed as 163 3/8"

I didn't think that the split line affected the solid body or the total length.

What am I doing wrong?

SolidworksParts And Features