I have been looking at the Automotive Performance Chip marketplace and frankly they sound almost too good to be true. Can a simple chip that re instructs your vehicle ECU actually give you a significant boost in horsepower, torque and MPG? There are number of brands out there, SLR and GForce are two I have looked at, both sell for $69.99 and claim simple stupid install with full money back warranty's. If they work as advertised $70 for more HP/torque sounds pretty good. I am considering installing one on my 2006 5.4l V-8 F-150 to boost its towing performance. So has first hand experience, pro or con, with these things?