With all the NVH issues (Noise, Vibration, Harmonics) in the standard IC engine, you'll not catch me running without some sort of vibration damper...
That said, the underdrive pully concept is not strictly limited to changing the crankshaft pully - you can increase the size of the water pump pully, alternator pully, and even the power steering pump pully to slow those accessories down, and gain the same net effect. I have recently seen OVERdrive pullys for the Delco alternator, checking around with outfits like March Performance Pullys can probably turn up "underdrive" pullys for the Delco alternator, the Metric Saginaw power steering pump, and maybe the Mitsubishi alternator used in the late model XJ's - I just haven't checked yet...
Meanwhile, I'll put a set on the drawing board, if there's enough interest. I've got a decent list going already...
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Additional - Since I've been a bit interested in this myself for my own nefarious reasons, I've put out a couple feelers - give me a few days, and be ready to give me some measurements just in case...
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