I was under my SL the other day changing the steering coupling (a very fun job!) and saw a blister in a 1/2" steel tube coming off the left side of the exhaust piping just aft of the equalizing crossover pipe. It runs back up the aft end of the engine compt. Is didn't look like it was leaking exhaust gas out thru the failure point, but probably will in the future. Is it critical that this tubing be in perfect shape and leakless? My guess is that this is part of the Cat system, since this is a California car. I couldn't find this tube on *************** to verify what it does...
Scott