I have Roe wrap and a high temp coating on the sills. With this combo I got them to hot and had a paint bubble.
I then took them back off and put on some reflective heat shielding on top of the high temp coating. Used a hightemp glue. With this combo they still get hot around the cat area (high flows) but not hot enough to cause any more heat bubbles. I also cut a vent hole in my front wheel well (not in pics) but the hole is not very big.
The nice thing about this, no extra rivots holding heat shields....
If I had to do it over I would go with the air flow thought. Air flow is the only way to cool the area. Stuffing the wrap in there is hindering air flow and holding heat in. My next thing I was going to try was the high temp coating with the roe insuclation cut and glued to the sill and the reflective stuff wrapped around the roe insulation. This would have a nice open area around the pipes for air flow. Add a vent in the wheel well, bam!