Do not bolt on parts from a mustang. They have differnt compression ratios, firing order, heads, intake, timing, and vacuum systems. A 1982-93 mustang firing order is 1-3-7-2-6-5-4-8, a 1979-1993 grand is 1-5-4-2-6-3-7-8. The best bolt on I can suggest is duel exhaust out the back with a pair of mustang shorty headers from
here