Until, someone has driven an IS with all the shocks mentioned (installed), I can say, you wont know which one is exactly the best.

Plain and Simple, the F-sport shocks were tuned to work as effective yet sporty daily driven shocks.

Lexus was not about to approve a racing shock for their f-sport audience, so they can, as the previous post said, loose control off road reflector.

Learn how to drive first, then upgrade

<3 you all