Intake Manifold/Header/Exhaust Help

I'm about to order my IM/H/E to install on my 93 Civic Ex. Is there anything I should know about them before buying them?

I was thinking about getting it all off ebay (noflameplz :D ) or from a shop called D2 Motorsports.

I just mainly want to make sure I know what not to get so all my sensors etc.. plug in and fit on the new ones.

Also, anything else I should know about installing this stuff before I do it? (I'm having someone who knows a lil more than me help)

Thanks.