Here's what I had to say about this in another thread:

SportCompactCar ran an article on this a month or so back. 1 EG, one CX; one powered by a K20 the other a GS-R head on an LS block. The b18 had low-level bolt-on mods(no internals), like intake and exhaust while the K20 was bone stock. The b18 actually put up better numbers, but the difference between the two was negligible. In other words, an LS/Vtec b18 will give you the same power for far less money, but if you're made of the stuff you can potentially squeeze more power out of a K20. Here's a link to the article, but it only shows you a few paragraghs becuase it's a little outdated. You can always order it if you want to read more.

K20 Powered Honda Civic EG vs. B18 Powered Honda Civic EG - Sport Compact Car Magazine

edit: also, if any1 read that super street magazine w/ the 10sec daily driven civic from Full Race, there's a top 10 list in that article on why ls/vtec is better than a k20.

edit #2: no word on how a b20/vtec compares