When Racing my RX-7 I used to have a top end hesitation. This drove me CRAZY! After getting fustrated with tuning the fuel injection system. I consulted several people and they all suggested that it was a ignition problem. Ray Lochhead suggested that I get some NGK Racing Spark Plugs. He said that RX-7's or in fact all rotaries love them. The plugs actually made a huge difference. These Plugs are quite expensive, but worth it. I actually wanted 10.5's, but these were the only one's that Mazda Competition had in stock. What better way to test them than to go racing the next day.
I tried everything before buying the plugs and had I known they would make that big of a difference, I would had bought them a long time ago. I was swearing up and down that my fuel management system was garbage, but looking back at all the changes I made when tuning, it made sense it was not the Fuel Injection System. Stupid me....
I want to thank SR Motorsports and Mazda Competition for all the advise they gave me.