Its really subjective. When I deleted mine I had all stock mounts in and yeah you feel some vibrations but its not horrible IMO. With the dogbone mount it gets a bit more but still fine. Forget about it if you have all three poly mounts. It literally was shaking my dash apart so I swapped the poly passenger mount for stock and it was fine again.
And I got a baffle kit when I installed mine. Works fine as far as I know.
And gonefhsn, you do know the balance shaft has to be properly lined up with the crank right? Just like timing cams to the bottom of the motor, the balance shaft is the same way. There are directions somewhere but i forget where.