Does it whistle when you shut down? Like a compression leak thru the valve seats. Or only when running or both? I ve only heard that when running, using 4150s when the throttle blades have the holes drilled in them to get the transfer slots in the correct positions. One is set to low and the air is being drawn thru the holes heavily. I know thats old school tuning, but thats how we did it...lol.
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