Since we mentioned a crack in a Brock exhaust system in the last CP, we have had four letters from EZ flyers who have had similar cracks. All report that they are hard to see and generally occur around the weld at the flanges. Next time you remove your cowling, take a bright light and carefully examine the exhaust system, paying close attention to the flanges. Look for a light grey deposit on the pipes or flanges.
Any cracks should be welded up before next flight. TIG welding is required for Stainless steel exhaust systems. Do not ignore a crack in any exhaust system. It may cause carbon monoxide to seep into the cockpit, or a piece of the exhaust pipe may depart the airplane and tear up your prop! Keep in mind that exhaust systems do not last forever, not on homebuilts, not on factory built, not even on cars! The constant hot gasses, heating to red hot, than cooling, all the vibration, etc., makes for a hard life. Check you exhaust system often and fix it if it is bad.