96 JGC fuel maxx Chip

I have a 96 Jeep Grand Cherokee that I just started to build, so far I have lifted and put larger tires on, I am in the process of building bumpers and getting skid plates put on, has anyone ever removed the carpet and sprayed in bedliner in the interior? Also has anyone ever used a Fuel Maxx Performance chip? The chip sounds to good to be true, says it adds 30 hp and ups to mpg by up to 4. I am looking for any info on either.