I own a 2009 v6 RAV4 base model with a short ram intake, and some sort of custom exhaust job (I did not install the intake or the exhaust)
When I take my foot off the gas I can hear a humming noise. I don't think it matters what speed I am going.
Due to the modifications listed above...
Started suddenly, does not seem to affect driving, no warning lights lit on dashboard.
While idling (from cold start) there is a humming noise coming from (looked under the hood, best guess) the front passenger side of the engine.
Humming gets louder when revving the engine while...