Go With Spectre
As far as I can tell, it does what it's meant to. I put this on before I put on my Spectre cold air intake to test it and noticed an immediate throttle difference, definitely added some power. And it hasn't messed with my mass air flow sensor. Don't buy this to save gas though, I haven't noticed much of a difference. Wasn't too hard to install either, just make sure you have a socket set and a pair of vice grips at least and you'll be fine.
2004 Toyota 4Runner SR5 V8
Very easy to install, helps allot with my MPG and horse power. installed Airaid Powerair throttle body spacer, K&N 63 Series AirCharger High-Flow Intake Kit and Jet Power-Flow Mass Air Sensor. With all of this now on the truck it makes and amazing growl around 3k rpms and the mileage has gone from 17.7 to 21.5 I am very pleased with all of these products and would recommend them to anyone.