Your picture shows the exhaust right on top of the rear master cylinder or is it an optical illusion? the heat that will come off the exhaust will boil the brake fluid try and get some heat resistant barrier in-between them if possible.
Are you ceramic coating the pipe? and if so are you doing the inside also?(which will bring the outside temp down a bit) I am still looking to get my pipe done so will be interested in your out come (and price) as I will probably send mine to the same place.