SSL do both a front & rear conversion (although the majority just have the front done) even with just the front on a 2003 car you should feel an improvement
I suspect it is not set up correctly, as this does involve a bit of bedding in and re-adjusting which is a little time consuming - but is not beyond the skills of most owners (even things like overtightened front shock absorbers [dampers] can adversely effect the ride)
