Wasnt that bad(for me), but this wasnt my first header install on a big engine with little space. It is time consuming and the use of wrenches, ratchet wrenches, stubby wrenches, swivels, and extensions is a must to make the job easier...also helps to have small hands.
I drive a service truck as a daily, so having the truck down is no problem for me, but the install can be done in a day by yourself and without a lift (although a lift would've made it alot easier). I would order a new set of the stock manifold gasket rather than using the supplied gaskets