I wouldn't cut corners when adding boost to your car. You get what you pay for. If you want something on a budget maybe go nitrous. Turbo and cheap are two words that don't go together. Only thing I know about the single vs twins is the single comes in a little slower than the smaller twins. Just personal preference I guess.

Remember that those hellion kits and most big named turbo kits include some of the air/fuel related components too....