[elhigh]

I don't remember all the rationale and I don't have enough engineering smarts to understand why, but when Hot VWs magazine was building their "mileage motor" project, among the other changes they added to the engine was to build up its rotating mass. They added a heavier front pulley and a heavier flywheel.

In terms of drivability it's nothing but gravy: more rotating mass gives the engine more inertia, so when you hook the clutch up you're less likely to stall it out. And since your Caddy is a manual, you might miss that extra mass when you're trying to get the rest of the boat moving at red lights. It'll change the engine from feeling flexible and torquey to touchy and rev-happy.

Rev-happy is fun, but not for hypermiling. Granted, hypermiling isn't a CTS-V's mission, but there it is.