New Headers for my '04 S

[Jaxonalden]

A heavy dose of penetrating oil, WD-40. Any lightweight oil will do then let it set for a day or two to work into the threads. Then prior to loosening and removing the bolts, fire up the car and allow the bolts to heat up. This is done to severely corroded bolts, mine just took a couple of shot's of WD-40 and the bolts popped right out.
One thing to remember, the heads are aluminum so don't over torque the bolts when tightening.

P.S. Give the O2 sensors a shot also.