Actually, B&G won't recommend using their flash while towing because of legal reasons. They sell their flash as "off road" because it may not pass emmissions testing everywhere. Since it allows more power to be produced, and more power to go through the drive train, the possibility of something breaking increases. They don't want someone suing them because they managed to break something by making more power. That being said, I can't tell you that you won't have any problems, but I have towed a filled 12 foot enclosed trailer 500 miles, part through the Smokey mountains, and didn't have any problems.

As for your seat of the pants power increase, it is probably the muffler for the largest part. The chip will change the shifts slightly, and may make a little more power in some areas. However, when I ran a Stage 1 on the dyno, which Jet has admitted to me that they have not done with a KJ and a 3.7, the computer compensated for the chip. It retarded the timing and and richened up the mix by about 0.5:1. That caused it to actually get about 5 hp less to the ground. I tried to work with them and give them the dyno results so they could reprogram the chip, but they were extremely rude to me. They instead told me that I could pay them another $400 and they would send me a custom chip that would work. They also claimed that they could make this custom chip without looking at the dyno results.