Do I need bolts to install this?

The flex pipe has the 4-bolt flange, but fasteners are not confirmed as included. Grab M8 or M10 bolts (check your vehicle service manual for exact spec) to secure it at both flanges.

Can I weld this or does it have to bolt on?

This is designed as a bolt-on flex pipe at the flange points. Welding is possible if your setup requires it, but the factory design uses the 4-bolt connection for easier future service and vibration isolation.

Will this work with a catback or full exhaust system?

Yes — this is a mid-pipe component that fits between the engine manifold and downstream exhaust. Pair it with any catback or cat-forward system that uses 2.00" diameter piping.