performance chip?

They claim better gas milege and increased power..any truth to this claim? I have a 2003 4 runner with v6 engine 89000 miles...runs very good...always can use better gas milege.

 

Nope, but welcome to the forum. There are some folks on here that are doing great things on tuning though.
https://www.4runners.com/threads/yo...lopment-and-feedback.21473/page-8#post-518150

 

A "performance chip" is just smoke and mirrors. You will get better mileage and performance just by keeping up on all the maintenance.

Yotawerx tuning, linked by @SlvrSlug posted above, is the only true way to get better performance but potentially at the cost of mpgs, depending on how it's tuned. They actually tune the ECU, not put a fake performance chip in somewhere to try and fool the engine into thinking it's seeing different values.