what is considered a good number for mpg for an almost stock LT1? i get about mid 14's to 15's with a moroso cai and dynomax bullet exhaust. i was getting 12-13 before those two things. is 15 mpg bad? i hear of people getting in the 17s and 18s, but i don't know if that's all city or city and highway. i think my car is running a bit rich, maybe not, but if it were how would i change the a/f ratio without having my computer programmed? thanks for your help.

 

All sorts of things can cause bad gas mileage, your numbers sound a little low. Check the fuel filter, quite a few times this was the culprit on cars i've seen.