Hi, I just bought an 06 STi and it has 18 inch wheels, 40 profile rubber, and Prodrive Springs and the ride is terrible. It is ok on B Roads but bounces on the Motorway. I want to go back to Standard Springs. What do you think? My research sez the Prodrives lower the car 20mm and stiffness is up 25-30%

 

I get the motorway bounce on just std suspension and 17" wheels.

The prodrive springs were meant to improve the ride, so perhaps the 18" wheel wieght and 40 profile are to blame?
Why not borrow a set of std 17" wheels and see what changes?

Nick