I have a slight exhaust leak where my Ypipe connects to the catback. You can feel a little air around the joint, but not really hear any sound from it. Just wondering how much that really affects the engine, and if it causes any performance loss. Im going to get it welded and take the clamp(s) off, but was wondering if it would cause any damage until then......thanks in advance...

If it's just a slight leak and you're getting it fixed soon don't worry about driving it. Just be sure to keep your window cracked a little in case of Carbon Monoxide. It shouldn't affect engine performance much at all.