I just installed a thunderheader on my 09 Nighttrain. I had Big Radius on there before and was averaging around 180 miles on a tank(about the same as stock). After my first full tank with the T-H, my mileage was about 120 miles a tank. The map I installed from the PC site was the only map with the T-H. It was an "advanced map". I am guessing it was overfueling, do I really need an advanced map if all I have is a screaming eagle filter and exhaust? Or could I use a map with any brand 2into1 exhaust?