Gains for MPG is 100% done in the timing table on these cars. And your right foot.

Most will increase the timing during "cruise" parts of the table to help get an extra 1-2 mpgs on the freeway.

I took a 2004 GTP file and ninja rigged it with my 00 GTP file. The 04+ cars got a more aggressive timing map than the older years, pretty much just have to combine them and make it nice.