Ride improved but:
1- Over any road studs I feel vibration and harshness inside the cabin (excessive).
2- Any imperfection in the road transfered into the cabin (not steering).
3- Not as smooth as what it should be specially a Lexus GS.
Improvements:
1-Steering improved and a lot tighter
2-Body roll improved
3-Nose dive gone
4-Sounds and clicks gone.

 

my 460 has always felt harsher than I think it should be over bumps and such, even after replacing suspension parts. on smooth highway its great. do you have 17 or 18 inch wheels? and what is your tire pressure?

 

In your case maybe this is how the AVS adjusted.
17 inch, 33-34 psi

 

Unless you have a new vehicle w OEM suspension to compare with or have a vivid memory of the car when it was new..... correct us if I am wrong.... what you expect may not be what the car ever was..... just saying

 

Maybe I am expecting something too high for an 18-year-old car, you have a point. For now, I will not do anything and leave it as it is and see maybe the new KYB's breakdown period is a little long and will soften a bit in a month.

 

I have a 2006 GS 430 with 125,000 km's on it in awesome original stock shape, including suspension, adjustable shocks, etc picked it up last year.
Was looking at SC430's, was thinking of the drop top.
Nice ride, but I was finding it a little "floppy" for me. Cornering was meh.
The GS 430's are rare here in Vancouver, they weren't on my radar so went to check it out.
Took it for a ride and wanted to buy it.
I bought it BECAUSE of the harder ride, the cornering ability, acceleration, awesome stereo etc, I'm also planning on F sport sways.
The low profile stock tires contribute to the harder ride.
My kid has a 2000 XLE, I have a 2005 highlander.
The GS is much harder than both, even with sport suspension off. The XLE is buttery smooth on bumps.
So the point I'm making is this might not be the right car for you.

 

Update,
I wanted to update you on my issue here, things are a bit more and less complicated than I thought! As it turns out the new suspension fix is fine ( a bit harder / sportier than OEM) but the ride did improve in the past 2 weeks after the shocks adjusted to the car. But I found out where is the real "harshness" come from.
I paid very very close attention to the car over bumps and road surfaces like studs, there is a dash rattle and interior noises coming from 4 places:
1- the dash
2- glovebox latch is broken (right) causes the box to shake because it is hanging barely secured by 1 latch
3- air vents (center) rattle.
4- passenger door (1 or 2 clips are missing from door panel)
The dash rattle is common on 3rd gen GS but if you have a bad shocks and bushings multiply the rattle by 2 times
I almost fixed the glovebox latch so it is secured on both sides now, and stuck another felts between the windshield and the dash (did it before but not enough!) , and am going to see how to replace the broken air vents. And for the door panel I remember when I replaced my front speakers a year ago some clips broke which caused this horrible noise and with bad shocks.. you can imagine.
I'll try to fix as much as I can. Thanks for your inputs as always you guys are awesome.

 

Thanks for the follow-up report on you suspension. I've had my '08 GS460 for a couple months now. It's at 175k miles. The engine runs great and I just authorized a transmission rebuild. Next is going to be suspension. It's a little squishy for my liking. I know it's a Lexus luxury car but I'm hoping for something a little stiffer...sportier. I don't want to lower it either. In fact I wouldn't mind an extra inch or two of ground clearance.
I think I saw someone mention tires but I was going to suggest adjusting tire pressure for harshness. You certainly don't want to go too low but you don't need to run around with max air pressure all the time either. The pressure increases as the tires get hotter so I usually air them up to about 10 psi below max.

 

KYB after market shocks are more stiff and sporty than KYB OEM, you can feel the car stiffness and way way less body roll around corners, if its your thing you gonna love it. Make sure to check your strut mounts too. And of course full alignment after that.
Last week I also replaced differential bushings, it improved the ride and acceleration, and since the worn ones cause a kick and a lag before and after acceleration, the car now is sooo smooth. I highly recommend to check those too if you want a "German" power delivery feel from your V8.
I will lower the tires around 29-30 psi and see how this might effect.
Thank you for your reply.

 

A passer by who just wanted to chime in. I have had the exact same experience as you do. I replaced the original suspension with KYBs, since like you said the OEM shocks cost as much as the car was worth (I’m exaggerating of course). But I didn’t do just the shocks, but a complete rework ie. control arms, ball joints, bushings etc. I wanted to do it once and be done with it as opposed going back and replacing some other stuff because they’re worn out a year later.

Having said all that, I was not happy with the ride. Just like you said, the car drove better but that’s a very low bar to pass when driving on blown shocks. KYBs felt harsh and the driving experience sucked. I hated it so much to the point that at around 6 month mark I jacked up the car again and did an extensive and thorough QC inspection, then resettling and doing the alignment. This was exercise did nothing.This was even more upsetting since everyone here praises KYB and says they ride the same.
Apologizes for my essay but I figured I’d share my experience since until now I thought I was the only one that had this issue.

 

You hit the spot, KYB's are good but not that good as many praised them. I guess for the price its ok but no way you compare it to OEM, nothing can match the OEM parts especially suspension setup.
For my case I kind of getting used to it but I still notice the lack of "Lexus ride quality".