The quickest and cheapest improvement would be to remove the airbox elbow that goes into the fender. Drive around for a while and let the computer adjust and presto! 3-7 hp more! Personally and many will agree, stay away from the K&N Fipk and most other cold air intake systems; it's not worth the money and you'll be asking for trouble/check engine lights. Do a google search and look up TTORA forums or Double Cabs of America and you will find a host of advice about making the best of your V6. I have a 02 TRD Double Cab with: Most of the TRD goodies: Supercharger, Cat back Exhaust, Thermostat, and airfilter. I drag race with my truck at the local drag strip and have been consistently running mid to high 14 sec 1/4 mile times.