I have a 97 D16y8 with 120k miles on it
only engine mods are AEM CAI and i run 89 octane gas with Castrol GTX 5W-30 syntec blend
i have noticed a signifigant loss in gas mileage since i put the AEM CAI on. no matter how i drive (even though i am at WOT all the time) i get around 25-28 mpg at best
before i put the CAI on i was getting 32-37 mpg depeding on how i drove. i put alot of highway miles on the car. i recently put a can of retore in with my oil change, and heard a NOticable amount of vaccuum increase( through the Bypass of the CAI, i can actually here it sucking air in at idle now, while standing over open engine bay, neverheard it before i put the restore in) but i still havent noticed an increase in gas mileage. i know it takes a few tanks before the Restore really starts working. but i am curious as to why my gas milage is so low? i know with the AEM CAI it is a lil more responsive, and i drive a lil harder cause i LOVE hearing VTEC kik in at WOT. but even when i drive like a grandma on highway i still dont get an increase in milage. the Best i can get on a tank of gas is 300 miles. i used to be able to get 400 (still leaveing one gallon of gas in)

what should i do? should i run HIgher OCtane Gas? ie go to 93 or Sunoco's 94? IF i do that will i not be able to go back to 89 octane with out getting pinging? (old myth) i recently had my TIming bElt replaced, and i am guessing that honda reset the timing back to stock 16 degrees i think.
should i advance my timing? like by 2 degrees? will that help with gas mileage as well as make the engine more responsive?
should i advance timing AND run better gas? will that increase the gas mileage, repsonsiveness, and make the car run quicker?

Thanks in Adnvanced
Dan