rich807 I agree with you. Changing the TFI for a powercommander might add a few more HP and it might not have been a true comparison.
If you look at the A/F Ratio across the whole RPM range, you will find some spots where the TFI units will not deliver the right amount of fuel. They might be a tad to rich or lean.
From experience, especially at the higher end of the RPM range, it does effect power, much if you don’t run a perfect mixture. You might get a HP here or there more if you get the mixture perfect, but not a massive gain as the dyno shows... I don't believe that the powercommander by itself will add a significant amount of power over a well set up TFI. When I 1st got my hands on the TFI, the 700R was making around 37HP. After some fine tuning of the TFI, we got it up to 42HP.
Also, note that I said that the powercommander was not tuned right. It was actually running a tad rich and no way near a good setup. So if you take into account that the TFI was set up quite well, plus you compare it to a powercommander that is not set up perfectly, you can make the assumption that the powercommander was not making a big difference and added a lot more power.
I will get the A/F ratio comparison between the TFI and the powercommander to show you that they where not way out. Both units supply fuel to the motor, and if the fuel delivery is similar between the TFI and powercommander, then the power output should also be similar. Not so?
Anyway, besides the fuel injection, the idea of the dyno runs is to show what happens when you add an aftermarket header.
The top end and over ref is much better. I dyno a lot of quads, and I get the exact same result on Honda, Kawasaki and Suzuki, when you change from a stock header to an aftermarket unit.
An aftermarket header will add more power, that I can guarantee you, so it is still worth the effort do add a full system. The headers design between different manufacturers are different, while the slip-on or silencer is very similar in design. A spark header might work very different to a GYT-R and both of those might be very different to a Pro Circuit.