Let's say I don't replace the pulley. What kind of performance gain would I see if I get rid the the resonators on the exhaust, put in a cone filter, and put in a speed chip? Do those HP chips on fleabay actually work? Thanks.

Stay away from the chips you see on ebay...if you really want to mess with your ECU....go through a known company...JetChips for example. Or take it to a shop and have them flash your ecu...pully swap best bang for buck..