With all the above mods it will be capable of getting better milage....as well as less milage.
I BELIEVE 90% of the milage depends on how it is driven. I drive like raped Obama so my milage stinks. If I drive like a church lady I can get VERY good milage.
Just my 2 dinar

EDIT: Tell your buddy to stop by and say hi. Just b/c we are ugly and smell, doesn't mean we bight!