[Chris Fultz]

From the rules, it is difficult to tell if this is legal or not.

Either way, though, have you considered this -

If you add the bumpers to these angled sections, you effectively make the hole in your chassis about 6" narrower - each bumper is 2-1/2 - 3" thick, and they would extend into this opening area.

Depending on how wide the opening is now (hard to tell from the picture) it might become very tight for a 9" game piece.

You might actually have a larger opening by having the front of the robot "flat" with 6" bumpers on each side, giving you a 16" wide opening.

I don't know how this fits in with you ball pick-up ideas, but something else to consider.