Do I need new gaskets or clamps to install this?

The system comes ready to bolt on at the catalytic converter connection point. You may want to grab a new gasket for the cat-to-pipe joint to ensure a clean seal, but it's not always necessary if your existing gasket is in good shape.

Will stainless steel stay shiny or does it need polishing?

Stainless naturally resists tarnishing and weathering, so it'll hold its finish without regular maintenance. A wash now and then keeps it looking fresh, but there's no special polish requirement.

What if the tip doesn't fit perfectly where it exits?

Test-fit before final installation to confirm clearance and alignment. If the tip needs slight repositioning, you can adjust at the mounting point before fully tightening down everything.