R&D goes into the development of springs from a reputable company like Tanabe. Crap companies build one size fit all springs and tell consumers put it on anything.

Personally, I think it is fine if you listen to my math.
GS 430 was around 3750 lbs
GSS 450h is around 4150 lbs

That is 400 lbs. Or 2 people in the GS 430. No long term, the extra weight may hurt the springs, we just are not sure and neither is Tanabe. Their R&D went into the other GS models.

Henry and Ryan touched on the safety part.

 

You also have to keep in mind that tanabe uses the same spring for all the current 3GS except the GS450h.

 

I use the Tanabe DF springs on my 450h. I was rubbing when I put on my 20s.
I've linked some pics of it lowered on another thread. I believe it was the wheel vs drop thread.

 

The car sitting low is certainly not the worst that can happen. If it were, I'd do it in a heartbeat. There's a reason that Tein or Tanabe haven't published that these springs work for the 450h.

We're not playing with go-carts here. With a 60K car, I'm willing to be patient to install springs that have been tested, etc.

 

If you want to say it like that... why go with springs if the car cost so much??? Why not go with fully body coilovers...

At the end of the day, its just a car that gets you from point A to B.