It's great to go and listen to speakers at stores, but you have to remember that the speakers are in a relatively sealed enclosure and are playing to to your ear level. Once its in a car door, the sound changes....

As for the highs not distorting, were you just using the deck on the wall or an amp to push the components?? Amped components will always sound much better and will not distort like deck powered components.

When you go and listen to speakers, try and simulate what you have in your car or will be doing to the speakers.