Let's do some math on getting something expensive like a tuner/chip/programmer...
Say your Ex gets 14 miles per gallon and you do 12,000 miles per year, the average an American drives. You'll use 857.14 gallons. At $3 a gallon you'll spend $2571.43 dollars a year on gas.
Let's say your chip/tuner gets you an extra 2 miles per gallon. Now you're paying $2250 per year.
Savings: $321 per year.
How much does the tuner cost? Banks programmer is $500 with tax (rounding here).
How much to install? $100? Free?
Either way, depending upon the price of gas, if it goes up and it will, it will be worth it in about 1.5 years.
If the price of gas goes down (not likely) 2 years.
If you drive less than 12,000 miles, that extends the time it takes to pay for itself. If you drive more than that it shortens the time.
And you run the risk of damaging your engine and drive-train by messing with the specs that a tuner does.