that advertisement is not relative to your 305. it will increase..something..but not a noticable gain unless you put air into it. 305 tbi's are equipped with the poorest of heads and the most restrictive throttle bodies along with a crap air cleaner and air intake set up, AND low flowing intakes AANNDD low flowing exhaust manifolds...SO..if you wanna get "alittle" performance this is what i would suggest. ditch the setup you wish for and check into hooker 2055?? or a set of headmens. make sure what you get are shorties..also you will need a y pipe that you can match up when you get your headers. NEXT, your tbi system has all the lovely smogger options on it and NO you dont need to remove them but YES i would highly encourage you to do so. purchase a set of NON A/I/R headers with an O2 BUNG already on the headers, unless your a decent welder and are capable of installing it yourself. also you'll need the proper gaskets for your header to y pipe application. it may take collecter gaskets or the donut gaskets. make sure you buy a good set of header gaskets as well..SPEND the extra couple of dollars on some copper gaskets or good standard gaskets TRUST ME..ALsO get a good set of header bolts, all the extra's can be found at a local parts store. now, thats just half of it. the next half is cat-back...putting a set of 1 5/8 headers wit 3 inch collectors on and connecting to a 2.25 inch exhaust with a 19 year old cat back is plain useless..you need to open that baby up to a good 3 inch remove the cat or get an aftermarket high flow cat 3 inch all the way to the tail pipes located just after your brand new aftermarket muffler!
now throw in a good open element air cleaner, some tbi mods, or go to carburated which i am in the process of..let me know if this helped you at all.
