+1. You need to fix it as soon as possible, or your engine won't last very long. You absolutely need to fix the problem where the exhaust pipe connects to the head. If the crack is in the muffler, way back from the engine, you can probably get away with that for awhile. It might cause the air/fuel mixture to be a little lean. Cracks can usually be patched. They sell stuff at auto parts stores to patch exhaust leaks. I would look on eBay for a good right side muffler assembly, or if you want, if both header pipes are good, you can cut the mufflers off and install Emgo shorty mufflers. They are a bit louder than stock, and may require rejetting.