20mm in rear and 17mm in front is definately the way to go. Do not think less as you will regret it. They line up with the outside fender. If you slam it then this may not work!!

I have found the hub centric - (4) delivered under $150! This is less than half of the H & R spacers.
Also easy to install . It really gives noticeable handling improvements and the wider stance is really nice!! It drives as smooth as without the spacers.

So for anyone interested, it is a DIY low cost mod upgrade for real performance and asthetics.