Maybe not, Bill.  Without the snubbers, there would be some unknown and
possibly variable delay in the closing.  There would also possibly be
varying delays between different injectors.  This variability might not
be enough to feel a vibration, but the exhaust pulse would be slightly
stronger from one chamber than the other.  It would only be detected as
more noise and would express itself as a slop factor in tuning.  Remove
the variability and the tuning can be more exact since the same amount
of fuel will be delivered every time, giving Tracy that extra 100RPM.

Possible?
 
         ,|"|"|,              Ernest Christley       |

Possible as anything else I can think of right now.  The 'variability' theory could explain a lot.  I know that the *average* mixture is the same as before (after correcting the IPW) but it is quite possible that there was a lot of jitter in the pulse width causing cycle to cycle mixture to vary a lot which the mixture monitor would not show.

 

I hesitate to throw more non-engineering terms into the discussion but sometimes those are the only clues we have to start with.  The engine does seem "crisper" and more responsive to throttle changes.  Very interesting that Steve perceived a similar change in engine noise too. 

 

Tracy (back from more house renovation)