stock rates for GCs for a civic (at least a hatch) are 375f, 250r. Not too agressive, but a definite improvement over stock. Once you have the perches though, you can get replacement springs for $50 apiece. So you could buy those, and if you find theyre not up to snuff in the handling department, $100 somewhere down the road could get you 400lb springs for the rears, which is something like my setup (400f, 400r), which is quite nice with yellows. Another thing to keep in mind when buying GCs is to make sure theyre compatible with whatever shocks you have... they have slightly different seats for different aftermarket and OEM shocks.

That bilstein setup looks pretty cool, but I'd check into the specs before I thought about buying it. And IMO, unless its just for looks, 2.5" is plenty low.