I use buick turbo performance(Jim Dunn).He is in philly,so depending where you are he might not be too far from you.He knows all about these cars,my car runs great since he worked on it!
If you can make it up to PA Jim Dunn 610-721-4695 is the MAN its worth the trip He's very reasonable and does very nice work.
If you can't get to PA try Anderson Performance 41 Long Creek Dr Stevensville, MD 21666 410-643-1515