Good information.
Both the slings have Welter exhaust with the Group 34 Optima battery. As recommended, position the battery to the left side of the tray. This has given us about 1 inch of clearance. We have been running it this way for over a year without any problems.
Mine ran almost 5 months, and mine was flush with the inside of the battery tray. Too close to the Welter exhaust pipe