You can try Outrageous Performance, they are in Jackson NJ (about 30 min south of Etown) other then that I can't think of anymore so jersey mustang-only performance shops.
94 Oxford White GT. 18" Saleen wheels with BFG Drag Radials. Vortech S-Trim, etc. 89 Oxford White Notchback. Chrome Pony Wheels, Full exhaust, Pulleys, yadda yadda yadda, 94 GT Vert (Stockish cruiser)