Will this piping need welding, or can I clamp it together?

This is bare piping meant to be welded into a custom exhaust system. Clamping alone won't seal exhaust joints reliably. Plan for TIG or MIG welding at connection points.

Does the polished finish need any prep before I weld?

Yes. Polished tubing needs to be cleaned with a wire brush or scotch pad at every joint before welding to remove the protective coating and ensure a clean weld bead. Don't skip this step.

What do I need to hang this system under the car?

Exhaust hangers and clamps are not included. You'll need to source rubber isolator hangers and U-bolt clamps separately to mount the piping to the chassis and keep it away from the body.