Go for the DC Sports JDM ITR 4-1 header. In a recent dyno test that compared this to the OEM JDM ITR, Spoon, Mugen, JUN, etc. the DC came out with some great numbers. Plus it's fairly cheap compared to some of the other options.
madtownhonda: How do you like the ARC? I haven't seen gains enough to justify the cost....do you think it's worth it? And do you have just the tube or do you have the filter box thing too?