Spring
 

would the civic 2001 sedan coil spring fit to 2004 civic SI? they both got Control-Link MacPherson Strut Front Suspension and Reactive-Link Double Wishbone Rear Suspension thnx!

No, they are different lengths.

^^^ what he said....

the si has a 5 lug bolt patter, its the same as a rsx or type S, you can get one of those suspentions.

Bolt pattern doesn't have much to do with the suspension. And the new Si will suck worse than the old ones. Somewhere along the line it gained 140 lbs, and it has the Base RSX brakes, not the S brakes. So its still overweight and underbraked. But get it now if you really want it, 04 is the end according to Temple of VTEC.
It won't fit because the Si springs are longer in the front and shorter in the rear. Do a search, I've seen the dimensions posted.

ah ok, thnx!