Can I weld or braze this aluminum pipe?

Yes — aluminum can be welded with a MIG welder using aluminum wire and argon gas, or brazed with appropriate flux. Make sure your shop has experience with aluminum to avoid brittleness.

Will this handle exhaust temperatures?

Aluminum loses strength at high continuous heat. If this is for a primary exhaust line with direct combustion gases, steel or stainless is the safer choice. For intake piping or secondary cooling lines, aluminum works well.

Does the black coating need prep before welding or installation?

Any coating — including the black finish — should be cleaned off the joint area before welding or brazing. Wire brush or scotch pad the surfaces where connections will be made.