Will this muffler work with my existing exhaust piping?

You'll need to confirm your current piping is 2.0" diameter. If it's different, you'll need a slip-fit adapter or a quick weld to match. The 3.0" outlet is universal fitment — most builders step up from 2.5" to 3.0" at the tip.

Can I paint or powder-coat this before installing it?

Yes. The muffler body can be media blasted and coated. Wait until after paint cures fully before bolting it in — fresh powder or paint needs time to harden around fastener zones.

What fasteners do I need to mount this?

Mounting hardware is not included. Hang it using exhaust hangers rated for your vehicle's suspension geometry, or weld it directly if you're running a custom mandrel-bent system. Check your build plan for clamp or bracket specs.