Do I need to weld this to my existing exhaust?

Yes. This is a bare tube section designed to be welded into your exhaust system. Have a shop TIG or MIG weld it in place for a leak-proof joint, or handle it yourself if you have welding equipment.

Can I use this as-is, or does it need to be polished or painted?

It's bare stainless and ready to install. You can leave it raw (it won't rust), polish it for a mirror finish, or ceramic coat it for extra durability. No prep work required before welding.

What's the difference between mandrel bent and regular bent tubing?

Mandrel bent means a tool is inserted inside the tube during bending to prevent kinking and collapse. You get smooth, consistent interior diameter throughout the bend — no pinching. That means better exhaust flow and no turbulence.