Its not that hard, but if the intake has never been taken off, you'll have to fight with the intake manifold support bracket. Its a pain.

You shouldn't have a probelm doing it.

Hp gain... Well... If your current intake has the TB injectoion looking intake ( but with 4 injectors still ) I'd say you'll feel a desent improvement, but if the current intake is shaped simular to the Z6 one, then you may not feel anything at all.

I swapped from a DX cam to an Si cam ( crx terms ) and didn't FEEL any difference...

D-series ownz BTW !! Screw the B. There is something wrong if you want more than 300whp in a FWD daily driven car... A D-series can make that kinda power with just rods/pistons/turbo.

SOOO... Don't talk down on the D.

Also, screw the intake/cam/header/TB crap. Grab a zex kit used for $300 and get some real power, then when you can get a turbo kit. After the turbo you can worry about all the little stuff. Why spend $1000 on 15hp, when you can get 80+hp for the same price ( via www.homemadeturbo.com )