C-notch question.

[rchavez101]

I will begin installing my C-notch on Thursday. I got under the truck earlier and seen that I will need to also cut the bed brace that goes right over the rails. What is the best way to cut it out? Do you cut out the section completely above the rail or just the thickness of the C-notch? I have the McGaughys Rear C-Notch. It seems like it may be hard to cut the brace with out taking off the bed. I don't plan on taking the bed off so any tips on how to do it would be appreciated. Thanks.