I recently discovered the exhaust manifold gasket is leaking on my 2007 4.7L. I am going to put this off until Spring, so I have some time to plan ahead. Has anyone else performed this replacement? Can you please share some lessons learned? I am looking at possibly purchasing Hedman Street Headers 79573, are these worth the performance improvement? I already have it tuned using a Superchips Tuner, Magnaflow Y pipe, Magnaflow muffler, and a cold air intake. I have read articles about block freeze plugs prematurely corroding and leaking in this motor, should I replace them while I have the manifold off? Are these concerns unwarranted?

Any feedback would be greatly apprecaited.