You may also consider a combination of a rear lower tie bar / sway-bar. The lower tie bar (attaches at the point where your main chassis bolt connects to the Lower C-arm) is a huge help in Honda's. It helps to really even out the rear suspension flex.

I have a GSR, use to Autox all the time, and have an upper bar in the rear, but with a Beaks Performance Type R sway bar kit. I couldn't ever afford the full lower tie bar/sway bar setups that Comptech and a few others make. I really like the setup with the Type R sway bar. Its a 22mm solid bar vs. the stock 13/14mm. It really helps to keep the rear end planted and typically gives controllable rotation at the limit. The Beaks kit includes billet aluminum reinfocing bars that help to reduce the tendancy for large sway bars to actually tear out the chassis mounts. You need integra rear lca's with this setup so that the lca's have the stock sway bar mount points. You can get them for 10 to 15 bucks a piece on Ebay.

Seems to have gone up quite a bit in price from a few years back but:

Welcome to Beaks Products

If you really have some cash at somepoint go for:

Sway Bar/Clear Tie Bar--rear (96-00 Civic & 99-00 Civic Si)