1999 Subaru Impreza Owner's Manual - Page 190
1999 Subaru Impreza Manual
Page 190 highlights
NOTE Due to the expansion and contraction of the metals used in the manufacture of the exhaust system, you may hear a crackling sound coming from the exhaust system for a short time after the engine has been shut off. This sound is normal. Catalytic converter D Avoid fire hazards. Do not drive or park the vehicle anywhere near flammable materials (e.g. grass, paper, rags or leaves), because the catalytic converter operates at very high temperatures. D Keep everyone and flammable materials away from the exhaust pipe while the engine is running. The exhaust gas is very hot. WARNING Catalytic converter OM-H0381 The catalytic converter is installed in the exhaust system. It serves as a catalyst to reduce HC, CO and NOx in exhaust gases, thus providing cleaner exhaust. To avoid damage to the catalytic converter: D Use only unleaded fuel. Even a small amount of leaded fuel will damage the catalytic converter. D Never start the engine by pushing or pulling the vehicle. 7-8