yo..i got this huge problem with the my suppension...i got a 91 vert S5.....i replace the the stock suppension with the KYB AGX Adjustable @ mazdatrix.com.....even though I adjust it on soft...it is still hella bumbee with i drive it.....do i have to adjust anything on it...when i first install the KYB AGX Adjustable..i replace all 4 of them. it wasnt bumbee...but it is now....anybody can help.....

 

If your using your stock springs they are probably the cause when paired with these shocks.

I have KYB AGX with racing beat springs and even on the middle settings it is a smoother ride than it was in 14 year old stock springs/shocks.

After owning many different shocks on trucks and cars, unless you live in an area with perfect streets shocks dont last nearly as long as people think. They are usually mostly worn out at 60k miles. People just dont realize it. Springs get stiff too.

But in your case it might be the fact that the stock springs are soft while the dampers are more designed for stiffer springs.

 

Also - tire pressure is a big factor.
If your Vert has stock tires, try 33PSI in the fronts, and 31 in the rears.