Mark, I agree totally with what you are saying. If I had an eccentric damper on my crank snout I would leave it on and look somewhere else for rotational mass reduction. However the other side to this equation is if you had a crankshaft on an externally balanced motor rebalanced using very expensive heavy metals, talented technicians and sophisticated measurement equipment to do the actual measurement, then it should work well in most cases.

I guess that I should temper my statements with the "it all depends" type of claim as even if the rotational mass is balanced, there can be other types of vibrations that can break off a crank snout (i.e. Miata), cause timing chain or belt issues and accessory drive issues. Sometimes even the factory engineers get it wrong when they don't calculate the service life and expected operating conditions correctly. Look at the old DOHC 3.4 Chevy, the Miata, 2.3L Sentra, etc..... I could tell you guys a story about the first versions of the now revered 7.3L Ford turbo diesel that would make you laugh out load.

You can replace the damper with a much lighter pulley just be aware that you may be shortening your engines life, potentially causing other durability issues and potentially reducing peak HP balanced against the potential benefit of quicker acceleration. Thats the equation you have to use.

Eric