You have to do the upper and lower intake together, and just the intake will make a noticeable difference. You don't need to do injectors at this point. Heads will make the largest difference, along with rear axle gears. MA will make more difference than the TB. Ditto for headers or exhaust.
89 Coupe, 369 big bore, AFR, custom Comp cam, Kooks, 3" exhaust, 11.6 @ 121 mph
04 Cobra, JLT 12" CAI, Magnaflow, Borla, Stifflers, FTBR Rr Susp, MM Frt Susp, 12.4 @ 115 mph
67 Cougar, XR7 GT, 462 FE, 4 spd, Edelbrock heads, PI intake, Global West