Which woul dyou choose and why.

 

I was between the two, but I ordered the s-tech because of the difference of linear vs. progressive on the front springs. Progressive provides for a variable spring rate depending on how much the spring compresses.

They've got the same drop -- and both will improve the handling as they transfer stiffness to the front, but the s-techs should improve the ride a bit more as smaller bumps in the road will be absorbed better in the front (where the Z is heavier). If I didn't care about ride or was more than an occasional trackster, i'd go with the RSR setup.

Just my opinion based on some research I did on these two setups (and user reviews).

 

The RSR's ride just like a stock 04 Z does...just sits a bit lower. Everyone who has them loves them!