EXHAUST FUMES SEEP INTO CAB CAUSING CONSUMER TO FALL ASLEEP. CONSUMER FELL ASLEEP ONCE AND WOKE UP AFTER HITTING A GUARDRAIL. LEAK WAS SO BAD THAT CONSUMER HAS TO LEAVE WINDOW CRACKED TO DRIVE. DEALER FOUND LEAKS IN JOINT OF THE PIPE. VEHICLE HAS BEEN TO DEALER 5 TIMES, AND MUFFLER WAS REPLACED TO HELP BACK UP.*AK