According to information I have been able to dig up, you need only replace the bushings. The rods themselves, I am told, are virtually indestructible. It is evidently a pain to replace the bushings only, but with the proper equipment it can be done. And are designed to be replaced. I am not entirely certain what the compression rods do or how they affect your suspension. Google: compression rods for Infiniti g35. There's lots of information available.