Modifying your car will definately help, but I think you should be able to beat the old EPA rating through driving changes alone.
The only other suggestion I have at the top of my head is to conserve momentum. Every time you use your brakes you are literally wasting gas. The heat from your brakes comes from momentum you invested in, but never used.
Also, look at your gains in percentages. 1mpg may not be much, but it's still 3.4%, which isn't bad. Hey, you're keeping up with inflation.
- LostCause