Since the MULTI ECU update, my car will at times (before engine warm up, under heavy load, or ascending a hill) will have a vibration and loud exhaust sound. It stops when I back of the slow down, but will come right back once get back on the gas. I had it in for a check, but could not replicate the situation. I have tried to record it with my phone, but it does not come out clear enough. Passengers in my care comment about the sound. Anyone else have this issue?