I have a question regarding the stock exhaust on my 2010 GMC Sierra 6.2L. When I drive up an incline and under acceleration I have this whistling/whining noise that happens every so often and didn't know if this was something normal or if I need to look into getting something replaced. Stock exhaust sounds great and there isn't much I would change, but have been looking at some of the forums and debating between the Corsa and the Borla if this could be something needing repair or replacing.