For springs I recommend Ground Controls. When you order them, you can select your own spring rates at no extra cost, and I appreciate that. They're also the only spring company that matches the sleeve to the shocks you have, so GC FTW.

They do have an off-the-shelf rate, which I believe is 350 front, 250 rear. For reference, stock CRX rates are 250/150. I don't know if they're the same for other EFs. I have 400/300 on my car right now, and I think that's about optimum for a street-modified rex. It's not optimum for a car with as much extra weight on the front as mine though. I plan to order GCs and Konis in the spring to replace my Skunk2/Tokico setup, and I'll be ordering rates of 500/400. If you're into autox, you may even want to get rear rates that are higher than the front. I know a guy with a stock CRX Si that is VERY good at autocrossing his car, his rates are 400/650. Koni shocks are good for spring rates up to 600 pounds, more than that and you'll need to send them to Koni for custom valving.