Do I need to remove the header to replace this gasket?

Yes. The gasket sits between the header flange and engine block, so you'll need to unbolt and pull the header to access it. Once removed, the old gasket comes off easily and the new one installs in reverse order.

Should I clean the sealing surfaces before installing the new gasket?

Absolutely. Scrape off all debris and carbon from both the header flange and block surface with a gasket scraper. A clean, flat surface ensures a tight seal and prevents the same leak from coming back.

What torque specs should I use when bolting the header back down?

Refer to your vehicle's service manual for the correct fastener torque sequence and values. Uneven tightening causes gasket failure, so follow the pattern closely and use a torque wrench.