i have a completely stripped truck, in the respects that there is minimum wiring and emissions. All emissions, a/c pump gone, all mechanical gauges (none of electric except fuel), dual batteries, cold air and running 35's with stock gear racio's and over 9" of lift.... so when i used the computer for a week just noticed minor over performance with fuel and motor response but to test this theory i luckily have a friend with the exact same truck and all stock too. All his wiring and emissions a- z was there and reading properly so i installed the chip in his truck and the gains where alot more noticable with gas mileage and motor response. it seemed he gained more lower end and overall basic efficiency and response so all in all i'd say it did its job for being an obdI truck