Here is some Gs data for acceleration runs, black with heavy steel flywheel, red with light weight McLeod aluminum and SPEC Stage 3 clutch. Either of them shift like butter around town, but I think that has more to do with taking 500 miles of easy driving when the Tremec TKO 600 is new.
Note the black steel spikes at shifts because the inertia of the heavier flywheel, but it then drops way back to provide the opposite reaction. The red recovers to a more useful curve and doesn't have as much of an inertia spike to as easily break tires loose in subsequent gears at shift. At start also note these are about from idle. The steel starts spinning all smooth while you can see the aluminum jitters a bit as it's recovering in the road inconsistencies upon rolling on the throttle. Also note the red produces a notably better start.
The aluminum is better in a Cobra in my opinion given the car is light. There shouldn't be a bogging issue with 500 ft lbs of torque if your carb is set up right. Keith Craft will probably bolt on a Pro-Systems carb, so you probably have that covered. I guess if the plan was to build a car to spin tires and make the car heavier the steel might be nice.
