Bryan Herter at pcmforless is one of the best LTx tuners in the nation. While not in the Dallas area, I would still give him a call and see what he can do for you. He did the tune one my 1997 Camaro LT solid-roller, stroker engine, which runs 10.60s @ 126.7 MPH.
Warren
Moore, OK
http://www.pcmforless.com/