Sorry about the late reply. I had to send mine back for warranty. They never told me what was wrong but they sent a replacement. It's been running great for the past year. I'm going to assume there was a few defective ones that slipped through QC.

Hi Xiao - I also have a new JR supercharger kit with the loud whistle / squeal. My fluid level also appears normal. Did you ever determine the cause of the noise? Or find a fix ? thanks robC Los Angeles