everything i have heard of them they are a complete BULL$ˇ37 they are fake. you will se just less than 10 hp and no mpg gain. because most of them lean the fuel-air mixture making more hp BUT hotter temp inside the pistons expect way less engine life and even less life out of your cats.
i personally dont have experience with them but every single person that i know always tell me to stay away of them. its better just to let the engine as it is.
There are chips that def work for specific vehicle. Think Corvette and other performance cars as they are retarded at the factory level for EPA, gas mileage, etc. However, as stated above, they don't seem Jeep friendly. In fact, Jeeps seem to hate EVERYTHING not OEM electronic wise, like the O2 sensors and such
__________________ '14 Willy's Edition Unlimited in Anvil '06 Rubi Unlimited, bone stock...for now. 3" Zone lift '94 Mitsu VR4, highly modified twin turbo '71 Stingray convertible, number matching & mint RetiredUSMilitary "I'd rather laugh with the sinners, than cry with the saints..."
I wonder what the EPA thinks of them on Diesel engines. I spent 21 years buying full size, 40' diesel buses, and no OEM engine manufacturer (DDA, Cummins, or Cat) will approve them. But then it's your 450-500k bus so do what you think is best.
Retired my 94 YJ 4cyl 5spd @ 200K
Now in a 04 TJ 4cyl 5spd CV @120K+
Both as a commuter vehicle in NW, NJ
April 2012.downsized and now a 99er.