[mr_mushroom]

the real key when you're going for performance is to get things that match the RPM range of where your power is.
you want the power where you drive it most.
so about that high-rise intake manifold:
there are a few different models, but most of them produce power at higher RPMs. usually their 'powerband' is in the 1,500 to 6,500 rpm range.
being that you're towing an rv(?) i guess, it might be better to get like a torker cam and manifold to increase your low-end power, as high-rise manifolds are generally designed to help with horsepower, at some cost to torque.
especially towing.
just remember that torque gets you going, and horsepower keeps you fast.

and always always match your components.
don't get a cam that puts all your power at 2K and a manifold that works best at 5K and a 3K stall speed.
yes, you'll go faster than stock, but not as fast as if you matched your components a little better.
plus make sure that your tranny will handle whatever you throw at it.
don't go building a 450hp beast with a 700r4.

good luck!