I deleted my 11 Ram 6 speed manual and wow what an improvement and way more than 3 mpg....check out the other posts on deletes and you will see my numbers. I now have a 16 Ram and won't delete until my 100,000 bumper to bumper extended warranty expires.
Good luck with your deletes.....as long as you don't have emissions testing, it is the way to go in my opinion.