My 49 is channeled over a malibu ch***is and pan, the exaust is all stock near the back it turns over the axle and down to the stock muffler. The bag is about a inche and a half from the exaust, I know the exaust is not that hot at the rear but is it safe, if not will racing header heat wrap be good, I know that you can touch a header if its wrapped. I realy dont want to modify the exaust since its new and sits nice all the way back. O yea, I bought the tall bags that get skinney as they go up, So when I lift up I get a little more room.
I second the heat wrap. I ended up having the exhaust run under my rear axle in my 51 and it's the bees knees! A little more of an expense obviously, but no heat issue to contend with ever again....
If you do wrap it, make sure you coat or seal that portion of the pipe with something first. My buddy wrapped the custom exhaust he made for his Harley, and they held moisture which rusted out the pipes.