If you get AGXs or GR-2s, it is reccomended by KYB (I emailed them) for you to not use a spring that is harder than stock or drops the car more than an inch. AGXs and GR-2s were designed for stock spring rates (2.1kg/mm F/R for S13). Not to say that you will not have success with the KYBs, but I am just passing on what they told me when I asked.
For an unmatched spring/strut combo (meaning a set that was not designed to work togeather on our car like the S-Tunes I preach so much about) I would get RS*R Race Springs and Apex'1 World Sport dampers (which run about $1100 for the setup) so that I had peice of mind that my shocks were going to last a long, long time.
Sorry to bash AGXs, but the only experience that I have with them is bad. I have 2 friends that have them and they have seems to turn to mush rather quickly. They both kept them on full hard full time (another practice frowned upon by KYB) and they have just had a short life. I do like KYB however. All Nismo suspensions are based around KYB dampers.
If you can save your milk money for a bit longer, get these. I've had them for a year (and paid WAY more than that) and I LOVE them. Stiff enough to make the car flat and track well through corners, but compliant enough for the daily drive. Girls compalin that my car is too "hard" while most guys love how connected the car feels to the road now.
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