Create Gap in Twisting Tower

Hi I’m fairly new to grasshopper and having trouble with a tower! I have a twisting tower made out of two mirrored towers, but I want to merge my touching plates (at the top and bottom) into one. I have attached my file.

ARC280 good vers.gh (22.5 KB)

ARC280 good vers_re.gh (28.3 KB)

Much more simple than I thought. Thank you so much!