im pretty sure i know the answer to this question. but i want to make sure.

will my sedan sit any different if i match up some z struts with my s techs. or will it be the same height. and it will be stiffer right?

 

Same height.

03-04 oem Z shocks will be the stiffest, but should be avoided at all costs unless you want the same bounce and freeway porposing that early Z's suffered from.

All other years of oem Z shock will be stiffer then you oem sedan shocks, but nothing to complain about.