Its an annoying resonating frequency that can occur in the normal cruising rpm.
I bought a fvd brombacher sound version, design looks like a factory muffler, its stainless steel, a-lot lighter than oem. It has no drone, at 2k rpm its about 87db in my garage, blip rev peak was about 98 db. Expensive alternative, but highly recommended.
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2000 Boxster S Ocean Blue Metalic
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