Well, I did the EMI headers, Flame arrestor, adjustable fuel regulator, and the re-programmed ECM. We ran 3, maybe 4 mph faster on the speedo. I had to get the timing adjusted from 8 up to 10 degrees. If I did it again, I would not touch the computer. It was nice running 87 octane and now I can only run 92. That proved to be a hassle at Lake Powell. I really don't think the computer made much of a difference. In fact, I'll probably have it re-done back to stock settings next season. The headers and flame arrestor, I would DEFINITELY recommend though. The boat is much quicker to plane and the mid-range showed the most improvement. I don't think those findings came from the computer. The only thing I have left to do is get a good fuel pressure gauge to maybe adjust the fuel some more. If you're in the market for EMI headers, call Don Baca at Triad Performance Marine. Excellent service from them. www.tpmarine.com (http://www.tpmarine.com)
In summary, you're going to spend less money and have really worth-while results by just doing the headers, arrestor, and maybe the regulator. You could do all of this for under $1,500 total! The Vortech kit is about $1,000 and does not come with headers.
Good luck!