The first two Houston shops that come to mind are
Turbo Pros (they work on a little of everything)
12003 Derwent Ln
77064, Houston TX
713/681-1111
M&D Distributors (mainly garrett and holset but may be able to help)
6931 Navigation Blvd
77011, Houston TX
713-928-5686
And the company that I have experience with
Turbo Power Systems
1860 Interstate 10 South
77707, Beaumont TX
409-842-9202 - Ask for T-BO
One of these shops should be able to help you, or atleast give you some guidance,
-Chris