i personally had a shop install mine, i tried to get those damn bolts off without air tools and it just wasnt happening, not to mention the car was on jack stands so i had very little room to work.
For Cliffsta: i would say that a header would give more power, i mean gaining 4 horsepower with a header is still more than gaining 2 with a catback lol, my one recomendation would be to get both with an intake, just having 1 or two of three doesnt work, you really need all three to see any difference, no matter how insignificant it is lol.