I have '89 305 with a turbo I can put a 3 bar map sensor and bigger injector, but i don't know the best way to go about the computer. I have all the wiring and the ECM, but can i get a chip, if so what would be best.  I don't want to put much money in it and i dont see why i would have to.  

You should lookup up Tuner Pro a gm efi editing software. It has become pretty popular. Also Moates.net has many cool tools for burning chips along with the ostrich emulator which can give you realtime reprogramming of your stock ecu. So now you could tune while you drive. These are probably the best deals for how much money you will spend trying to deal with fuel enrichment. Also do your homework, many people try to get you to spend money on features and components you don't really need. Remember when you increase your pressure range you will lose resolution in your fueling map, the change between each point on the graph becomes larger. So only use the minimum bar pressure scale that you need, theres no need for a 6 bar sensor if you are only running 1 bar and under. Anyway those products should keep your budget down with excellent results.