I have an '08 SRT8. When I start it on a cold morning (below 20 degrees), it makes a quick "whoop" sound just as the motor kicks in. I don't think it is the serp belt b/c it doesn't do it as the starter is turning the engine...it makes the noise right when the motor starts running on its own. It won't do it if it's warmer outside or the engine is warmed up. I'm guessing maybe the master cylinder or power steering pressurizing. Any ideas?