Motorcycle Repair: hesitation, screaming eagle pipes, stock pipes

Question
I have a 2004 1200 sportster custom with approx 1500 miles. At 150 miles the dealer installed a high floe air cleaner and screaming eagle pipes. I put the stock pipes back on as the eagles were too loud for me. The problem I have was happening before I changed the pipes back to stock. I love the bike but when starting from a stop in first gear the bike has a hesitation if you are fast on the throttle. I have had 7 harleys and never experienced this before. Its almost like it has no gas if you hit it hard. When first warming up when the choke is out half way it is smooth as can be. How can I fix this? This makes riding the bike a little frustrating.
I also get an occassional backfire through the carb. I'm sure this is just a minor adjustment but the dealer tells me its fine. I don't have the confidence to pull out quickly into traffic. I am an experienced rider with ten years of riding experience and over 100,000 miles of saddle time.

Answer
Your bike came from the factory lean to pass EPA standards. Adding the air filter and pipes made it run even leaner.
What you need to do is add a Dyna-jet kit to the bike. This will fix the problem and give you better throttle responce.
You can install the kit yourself. You will need to remove the carb and by following the instructions that come with the kit you should be fine.
Good luck and happy riding
Mike