Because the front end on the newer Xs are coil over and have a completely different set up, including steering!

The 1st Gen Xs have torsion bars... the set up is limited to 3"... however, on the brighter side, the 1st Gens actually get that 3" in extra flex... the 2nd Gens just get their whole guts moved down 5".

Poke around this site, lots of great info.