BEst I could tell it works as advertised. I added a couple of other items at the same time. I had Gibson Cat-back, Gibson headers, Jacobs Ignition, underdrive pulleys, and K&N Air Filter. This set up was awesome for power.
If I had the money now I would do all the above except the pulleys (no charge at idle) on my Tahoe. I still have the Jacobs unit and will be adding that to the Tahoe. I would put a throttle body on my Tahoe if I found one at a good price.