I learned the hard way after spending about 5000$ on my Scion tC (over the past 6 years). Just random modifications and constantly changing parts because of "new" reviews and dynos showing different results. In the end, I only gained 23whp and 15wtq.....depressing huh? I could have saved that money and bought a turbo kit putting me at a 120whp gain and 100 wtq gain....better result.
With the Ranger I'm taking my time and just doing functional modifications for the driving I will do with it (pavement and some 4x4). I have read many threads on here and other forums that intakes are essentially worthless for the trucks as the OEM style is very efficient (for the 04 models at least). All I am suggesting is that you thoroughly review and think about every mod you spend money on for your truck. You'll regret it in the end if you spend the money and you don't get the results you feel you should have......you also learn to not like the vehicle much after that.
My incentive to keep my tC, though.........5-speed manual and 32 mpg (I drive 52 miles each way to work). The truck is my "relax and enjoy" vehicle.
2004 Ford Ranger 4x4 XLT.....4.0 V6....4.10 rear
2" torsion key crank
235/85/16 Goodyear Duratracs
Gibson exhaust (POR20 coated)