Hi

Does anybody have any good ideas or advice concerning an exhaust upgrade that would involve deleting the oem "turbo" muffler and replacing it with it a longer pipe . ??
Jeeps rock

What model and year Jeep do you have?
Basically you can rip out the stock restrictive muffler and replace it with a similarly sized performance muffler. There are many mufflers on the market and this page will give you some idea of what's available:

http://www.jeep4.0performance.4mg.com/exhaust.html

The stock cat is also restrictive so you can replace that as well with a Carsound high-flow unit. If your Jeep only sees offroad duty, you could just replace the cat with a piece of straight pipe.