So, the flex pipe on my good old Mercury Mystique is almost fully cracked on one end. The place where the flex pipe and braiding are connected to the solid exhaust pipe is only about 25% intact. The result is that my car sounds like a hot rod when it's running, has about as much power as a scooter, and is likely leaking carbon monoxide and other nastiness into the cabin. Obviously, this needs to be fixed. Normally, I'd take my car to an exhaust shop to have it fixed. This time, I have neither the cash (likely at least $600, but probably more like $800) nor the inclination (spend 800 bucks on a car that would sell for 500? no thanks!) to have a pro fix it for me. So, I want to do it myself. I've already purchased the proper length of flex pipe with the intention of grafting it in. I have a saw to cut out the old pipe, ramps to get under the car, and flux-core wire welder. So, mechanically-inclined friends, have you got any tips for me? Can I weld in the new pipe while everything is attached to the car, or do I have to remove the exhaust system and weld in the new flex pipe on the bench? Can I save myself the hassle of welding the pipe and simply clamp it in place?