Matt's right, #1 can be a little tricky, but is doable if you're patient. I wouldn't say the underhood temps are any worse with the Hellion kit as opposed to any others. I just ordered the heat shield on Friday, and wrapped a section of my downpipe with header wrap to cut down on burning my plug wires.
1991 LX - Turbo 5.0
Old Combo...Stock block and heads, Turbonetics 62mm...6.78 @ 104.25 - 436rwhp/508rwtq @ 10psi
New Combo...Boss 347, TW heads, Super Victor, Cam Motion cam, Precision 78mm, Big Stuff 3, etc...