You would be surprised what $500 gets you in a coilover today.
Working in the suspension end of this business since 1998, and for KW's original North American importer and then running KW USA for 4 years I have quite a broad range of experience in this area.
The kits in the range of the Solo Werks and FK Streetlines etc are comparable to many of the higher end brands in ride quality and handling - in my experience it comes down to how long the product will last. With Warranties of 3 years on the Solos and 1 year on the Streetlines you can see where the companies are putting their money into as far as seal/rod quality etc.
For example, selling FK's for the last 10 years at AMI the warranties we have seen have been mostly the seals inverting due to the chrome piston rod having burned through.
In the end, barring any installation issues the ride quality is always a subjective thing as everyone likes a different amount of salt in their soup.
We have a large amount of customers that love their Solo Werks, some that say they are too soft, some that say they are too hard.
trutone, you have a PM
