If your not using A/C in a civic, you can use the Integra radiator. Good suggestion. I decided not to do it with mine because I was considering a turbo and wanted as much room infront of the engine as possible. Integra radiator will fit but you need to custom make the lower mounts and chop off the stock civic A/C mounts.

Edit: Since somone's probably going to mention it too, there is also a dual core (twice as thick) radiator that you typically find in Del Sol VTEC's but you can usually pickup an aftermarket stock/replacement part that is dual core as well for less money than a fluidyne. A good investment if you just want a modest increase but like I said, I decided to spend the money and just get a fluidyne.