To answer your questions
1. Amperage Tech
2. Jeep boards or Jeep Stuff
3. To go an exhaust shop and get a custom high flow exhaust bent. Ditch the cat or put in a resonator, increase the diameter to 2.25-2.5", get a decent high flow muffler, and make sure all the piping is mendrel bent. Should cost around $350. I had mine done at Minute Muffler 5 years ago and has worked great. Also if you need a new exhaust, re-route the piping down in front of the oil pan and then back to the muffler.