Custom Stringers and Blank Width

I am going to get some custom stringers in my next batch of blanks, including some wide colored classic foam. I am wondering if adding say 2" of stringer and foam will increase the width of my blank by 2", or perhaps they discard 2" from the center of the blank to retain the dimensions.  If they let the blank get wider with more stringers, this could be an easy way to get a custom short wide shape, or it could also be a way to get weak soft rails from a traditional shape.  Can anyone with experience offer input?

Just ask them to make it in the width you want.  The closer your blank is to the final shape, the easier the job will be.  The more you take off from the outline the thicker the edge will be.  Use the tapered rail of the molded blank to your advantage. 

I recently ordered a blank with two 3" foam inserts to get a wide blank.  If it was just the colored insert I wanted they could have removed the same amount of foam to keep the dimensions as originally designed.

Thanks for the tip.  I have had the problem before where I remove so much of the rail that the existing taper in the blank seems pointless. Starting closer to finished would work well when going narrow.