Hi,
Yesterday I was driving home and gave it some gas in third gear and noticed there was a whirring/whining noise coming from the rear that got more high pitched as I went faster. Then it stopped after I changed gears and kept going. Today I tried to reproduce the noise because I was scared, but I didn't hear it anymore. I don't wail on my car daily, never launched it, or abused it. It's just a weekend cruise car. I hope it isn't a drivetrain problem or something? I tried doing a search on this topic, but all the results that came up don't answer my question.

Thanks

 

What mods if any do you have?

 

Just a catback and air filter.