A piece of hose for your ear, Keeping it at the exact same spot for each one's 'hiss' for comparison - Seems equivalent, These are equal. The left flywheel pictured is the earlier Silvertop design when the best could be the lightened Blacktop. The OEM 20V idle Command solenoid (ISCV) https://patrickp305jsb8.bimmwiki.com/user