Here are a some methods off the top of my head -
1. Lighten your truck as much as possible.
2. Relocate your battery to your drivers side, lengthen your Air Box wires to reach the passengers side, and put a Cone filter like 6 inches upstream from your throttle body.
3. Place a small hood scoop directly above your cone air filter.
4. Run a 4-1 Header for max power, or a Tri-Y (4-2-1) Header for strong mid range.
5. Run a "true" 2 1/4 exhaust system with a highly free flowing muffler, like a DynoMax, and then use a variable exhaust backpressure tip, like a Nology T.REX or a VariFlow control valve for ideal low RPM - crawling RPM - backpressure and top end.
6. Upgrade your ignition. Use some Nology Hotcore wires and some MSD/Jacobs/Excell/Crane/etc coils/cpu/etc.
7. Use Toyota Iridium spark plugs.
8. Do the Air Box mod to get a richer mixture.
9. If you dont live in Alaska, Add a shut off valve to your water jacket line leading to your throttle body. This will drop your throttle body temps by more than 100 degrees resulting in cooler intake air charges which is denser and can hold more parts of fuel per parts of air molecules.
10. Do away with the valve cover oil bypass line. Use a small dump filter or an oil catch can.
11. Ceramic coat your header. This is a must.
12. For great cooling, cut away your inner fenders.
13. Although it is not as reliable, run an electric radiator fan, I recommend the Black Widow (Magic?) fan, and get rid of that power-robbing belt driven fan.
14. Get a MSD Engine Knock monitor system and advance your timing to the max.
15. Place a simple switch controlled air solenoid on your EGR valve, disengaging its function resulting in 100% Fresh air intake and cooler intake temps.
16. If you dont care about your engine, run a thinner oil. I would not do this though..
17. Get a MSD RPM swtich and setup a very low pressure or think mist water injection system for use above certain RPM levels for hard hill pulls/climbs. This will take your actual intake air charge regardless of outside air temp down to about 40 to 50 degrees F. This alone will add about 10 to 15 HP if your fuel system is to par.
18. Put underdrive pulleys on your water pump and alternator.
19. Run an oversized throttle body.
20. Change your cam.
21. Run an adjustable cam gear. Is this even made for SOHC R-series?
22. You could always port and polish your head, or run a 20R head with the intake tig welded and surfaced to accept your EFI intake manifold, put larger 22R valves into the 20R head, and port and polish it. Make sure your polish your dome and get it ceramic coated along with the valve bottoms.
23. You could always run a turbo or fab a SC, but I suggest against this.
24. You could always squeeze some juice (aka NOS), but I suggest against this.
25. And lastly, Lighten your truck as much as possible.
Regards,
BigMike