[OAC_Sparky]

Open your hood while the engine's running. Gun the gas, you'll see the engine pitch and roll.

The factory mounts are very soft, because the primary function is to reduce vibration to the cabin.

Poly engine mounts reduces that rolling action.

This is useful because 1) the energy dissipated in moving the engine is not being put to work at the wheels, and 2) a rolling engine throws stuff out of alignment.

The first is pretty obvious, not that it means that suddenly you have more hp/tq. It just gives a little less lag off the line.

The second is a bit more important. When the engine and tranny rolls, everything rolls with it. Stuff like your shifter linkage get out of line, very pronounced on the 1-2 shift. Personally, that is why I got a VF rear mount. Between that and a Steeda short shifter it made a huge difference. Nice crisp shifts.