Matrix and Vibe springs are identical, so you can order them under either name. I got mine from:
http://www.optauto.com/webstore/product ... pt=1680for $143 plus shipping, listed for Matrix. They look really well made and gave the specified drop of just over 2". Ride was just like stock and handling was great, much less tendency to lift the right wheel on hard right turns. Unfortunately, per my recent "suspension' post, my monster tires scrubbed on combined bumps/turns and I had to go back to shortened stock springs. For sure there would be no problem with up to a 235/40 on an 8" rim.