absolutely, just like throwing a deck chair off the titanic helps.
seriously though....20lbs less of rotating and unsprung weight makes a MUCH bigger difference than 40lbs less exhaust weight.
take off the donut and u save ALOT of weight... as mentioned loooooooooooooooong time ago... so lets do some math...
Car weight - watever weight save u guys talked above - no donut = X
Now find X!
X <---- here it is... ^_^