I usualy go to euro sport its up in plano and about 50 miles out for me but its worth the drive knowing that your car is in good hands
They do very good work with everything, and do even better if you wish to upgrade.... my buddy got his TT chipped and tuned there the other day and was pulling a cool 300 hourse power when they where done, of course they could have done more but for an every day driver your don't need to much more
http://www.eurosportplano.com/
They also use state of the art machines autorized from the manufacturers like audi and porche, it's just something they have over your every day mechaninc shop