New exhaust system at 18,000 km ! Last March at 6,000 km, my Blazer started to make a metallic noise when accelerating between 1,500 and 2,500 rpm. At first I was told that it was normal but by dint of insisting on looking for the cause, the noise seemed to come from the resonator. So my dealer ordered a complete new exhaust system ($1,500) and installed it last week. No more noise ! I'm so happy now and I'm glad how quiet my Blazer is. Since my exhaust system has been replaced my fuel consumption has dropped considerably and I have a lot more power. When I'm in 2wd mode, my front wheels spin very often now and I haven't changed my driving habits. After driving for over 5 months with a faulty exhaust system, I have probably developed some bad habits. So if your Blazer gets noisier under acceleration between 1500 and 2500 rpm and it uses more gas, your exhaust system is probably faulty.