Headers are not a waste as anything allowing the car to breathe better is ok. Probably get a few mph improvement over the stock exhaust manifold... Throttle body spacer is a waste as mentioned. And you'd be better to save your $ and get your own tuner. While saving read up on how to tune and be ready. Overall on an NA engine you are only going to go so far, so those investments will not get you a great return on your investment, whether a canned tune or doing it yourself. Bottom line is you need a plan on what you want the engine/car to do. A tune will not magically transform the engine into something it's not! But it can make it perform more efficiently in HP or Economy up to its limits.
Overkill is a good guy but does the tunes as a side business not his primary, so patience is required. If going the canned tune route I would recommend his product over all others!
Good Luck!
