Do I need to drain the whole cooling system to install this?

Yes. Expect to lose your existing coolant, so have fresh coolant ready before you pull the old radiator. Flush the system while you're in there—it's the right time to do it.

Will this work if I've modified my cooling system?

This radiator is built for stock configuration. If you've added an electric fan, different pump, or non-standard hoses, test-fit before committing. Factory mounting and connection points assume no modifications.

Are hoses and clamps included?

Radiator core only. Reuse your existing hoses if they're in good shape, or source replacements separately. Clamps are separate too.