The problem with your website is that it takes too long to discover whats available or I am doing this wrong.
For example if you have no ES44acs then the engine image of the ES44ac should be grayed-out. Otherwise I spend too much time click at each image to find that nothing is available.
Just a suggestion
Thanks for the suggestion AlanRail.
We have wanted the ability to "Hide" categories with 0 quantity for quite a while. Trust me if, we could get this to work we would. Unfortunately this is not an option currently with our E-Commerce software. We have put this request into the E-Commerce Software company multiple times, but it has not been added as of yet.