Nothing you buy is going to significantly get your money back in terms of MPG gain. If you're after MPG's then sell your truck and get a car.
For example, you listed the Pulsar. Prices I see are anywhere between $475 and $525. Let's just go with $500 to make the numbers easy. Let's make some assumptions on numbers to make the math easier: You get 16 MPG average (don't know what truck you have, but that's about what I average), the Pulsar gets you a 10% increase, and you pay $2/gallon of gas, and you fill up 25 gallons exactly every time.
1 tank of gas before Pulsar: $50 for 400 miles. (16 mpg)
1 tank of gas after Pulsar: $50 for 440 miles. (17.6 mpg, 10% increase)
40 miles / 16 mpg = 2.5 gallons of gas or $5 saved.
You'd have to go 100 fill-ups, or 44,000 miles, to get your money back. Average of 12k miles per year, and you're looking at almost 4 years to recoup $500 spent. That's if you even see an increase.
