You should try a D16y8 or Z6 intake manifold. You have the D16y7? Correct? The y8 is probably the better of the 2. Its a pretty easy bolt on project as long as you have everything you need.

Here's a site you can check out .
I dont recommend using sealent like they do in the IACV opening but it will give you an idea of whats involved.
http://www.makuragi.s5.com/civic_99/Y8maniswap/

Hope this helps
Dog