Gears...its not for the engine, but gears make all the difference in the world.
If your staying N/A - 4.10s
If your Blowing or what ever - 3.73 at the LOWEST!
-My friends 93 -11-Second Mustang (5 Oh)...
You could try these...
**PROBE forged pistons and rods ($350)
**EAGLE custom ground crank ($375)
**FRPP E303 Camshaft (535 Lift) ($190)
**AFR 165 stage 1 ported & polished heads ($1,600)
**CRANE Cobra 1.72 roller rockers ($240)
**FRPP 93 Cobra upper intake ($250)
**GT-40 lower intake (port matched) ($350)
**FRPP 24lb injectors ($190)
**MARCH underdrive pulley's ($100)
**BBK 70mm Throttle Body ($190)
**BBK Cold Air Induction (fender mount) ($150)
**Pro-M 75mm Mass Air Meter ($230)
**K&N conical filtercharger ($30)
**FRPP 9mm plug wires ($50)
**AUTOLITE spark plugs ($25)
**Timing set to 14' BTDC (-)
**Complete ARP engine bolt kit ($150)
**Aluminum HD Harmonic Balancer ($385)
**MSD Billet Distributer ($280)
**BBK Unequal shorty headers ($150)
**HEDDMAN Off road H-pipes ($120)
**FLOWMASTER American Thunder aftercat ($260)
Gears first of all. Depends on if it is manual or auto. I would say 4.10s for auto and 3.90s or 3.73 for manual. Some other cheap things to do are, make a home depot cold air kit. Then free up the exhaust, header, off road pipe catback. Then he could think about a new intake manifold. It all up to how much you want to spend. Also put the car on a diet. Remove some weight, there is a complete list somewhere. Things like removing the dogbone weight etc.