Possibly...hard to say without knowing how their actual performance is.Can you beat that...even with DIY?
What differences are there between the XT25 "car" version and the regular XT25? Just the mounting flange?
Because the XT25's are pretty renouned for having poor off-axis response....I would be a little worried about using them sucessfully in a car without knowing whether or not the off-axis performance was improved.