I am getting ready to redo my entire exhaust system, and I know it will be hard to remove the rusted header bolts. I have seen some threads of guys talking about soaking the bolts in some sort of rust remover for a few days and that helped considerably. What is it? I think it started with a P. Any help on how to remove those bolts would be extremely helpful.

 

Heat is your friend on this one. You can use any penetrating oil as well. Let it soak in overnight.

 

PB Blaster- get the good foamy stuff.. spray it on when the engine is nice and hot, and tap the bolts with a hammer to get it up in there... do that a few times over a period of days or weeks..
when the time comes to take it apart, do it when the engine is nice and hot. spray it, pound it, loosen it..

you say you are redoing your entire exhaust system- which i interpret to mean that you are taking the manifolds off and going with headers.. if that's the case, don't get too bummed out when the studs that hold the y pipe to the manifolds break.. you won't be reusing them, anyways.. and also make sure you bend the little retainer tabs on the manifold to head bolts out of the way before trying to put the socket on..