Eric, the exhaust work should be done by some experienced with it. Most exhasut have to be bent to follow the original piping and most people don't have the tooling to do this. The engine should not have to be dropped to fabricate an exhaust based on the same routing as the factory exhaust. If you want to route the exhaust differently it will be a lot more work.
basically you can take your car to any muffler shop and they can bend an exhasut the exactly matches the factory. Basically what they do is that they cut off hte old one and bend the new pipes to match with the original pipe. Then this new piping can then be bolted back up into the same area.
You can either go with a crush bending or mandrel bent exhasut piping. Mandrel bends is more of a perfomrance exhasut and will be more expensive usually.
So to answer your questions
1) it isnot tough to fabricate your own exhasut if you know what you are doing and have the proper tools ie: muffler shop
2) The engien does not have to be removed unless you are installing a custom designed system.
hope this helps some. Any more questions just ask.
