Not an engineer, but wouldn't the computer simply compensate for the increased air or efficiency increases by reducing fuel to maintain temps or other parameters in spec? It would seem that without a reflashed computer to take advantage of the efficiency gains, all you're doing is dress up an otherwise underwhelming engine bay. If you went for the whole package, you're looking at 3-5 grand and you give up a warranty. Although If you have that kind of money, maybe the warranty isn't critical. I may be making a broad oversimplified presumption. However, I do want the exhaust because the stock exhaust is so horribly large.