That's an interesting thought. The exhaust volume should go up with the engine rpm, but the raspy tone just can't be duplicated by reving the engine. However, it may sound similarly during higher rpm (5k+) driving.
Quote:
Originally Posted by ta-kid
I would argue that it has anything to do with the cats that the tone changes approximately 10 seconds after a cold start up.The rpm does not change either much if any in the first minute or longer for me, but the tone does go from a harsh raspy note to a softer note within that 10 seconds,like there is an exhaust valve in the system somewhere closing.I wonder if the ECU is changing the variable valve timing once the cold start has been sucessively established?
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