What little things can i add to add performance to my 1967 289 mustang?
If you have a motor that has 10 to 1 compression and stock heads then that is the ammount of HP you are going to get. I know dummies back in the day that used to have 70's
camaro's and with junk 350's and thought if they put dual four barrel carbs and intake on it, they could get to 400hp. Not the case. If you have 200hp heads most likely you will get 200hp. If you have 250hp heads you will get 250hp, so forth and so on. You have to step several things up to achieve HP. Compression, air flow, and valve timing via the cam. You can sit a 55 gallon barrel of gas on top of your engine and have it dump a gallon a second into it, and still not do anything but dump gas out the tail pipe...
I will say, if you haven't already, change your distributer. If you still have the old points distributer you can change it to new electronic timing modes with boosted firing power for about the same you would spend for a carb. Needless to say points need to be changed and adjusted seeming like every 6 months, what a pain...