Are you talking about the black plate the bags sit on? My stacks also hit the back end of them where they drop down a bit. I just took them off, then cut off that dropped down rear section. Been that way for 7-8 years now with no trouble or overheating the bags.
Yes the black heat shield is what I was referring to. I didn't know if there would be any issue with trimming that. Didn't want to risk heat damaging those REAL expensive to replace factory bags. Did you just trim away the section that steps down on the very end?