Do I need clamps to install this?

Yes. Clamps are not included with the hose. You'll need two hose clamps rated for your application — one for the 2-inch inlet side and one for the 2.25-inch outlet side.

Can I use this on a coolant line or is it boost-only?

This hose works for both. The 3-ply silicone handles turbo and intercooler boost applications plus coolant circulation. Make sure your clamps and fittings match the intended pressure and temperature of your system.

What if my piping is 2.25" on both ends — will this fit?

No. This is a true reducer that steps from 2-inch down to 2.25-inch. If both your lines are the same size, you need a straight 2.25-inch elbow instead.