I30 is loud when cold...

[MattB]

When my car's engine is cold and I start driving, between ~2000-2500rpm or so the engine gets noticeably louder then subsides above that RPM level. Once I've driven the car for a minute or two the noise goes away and doesn't recur. It doesn't have to be stone cold, just has to sit for a couple of hours. Is this normal or is there something wrong with my car?

[quiksilver20004]

More than likely what you are hearing when you start your car up after sitting a while is the motor pulling in a whole lot of air. When you first start up an engine the intake air temp sensor shows that the car is pulling cool air and enriches the air to fuel mixture and therefor pulls a lot more air than usual making a loud sucking sound.