Some back ground on heavy flywheels....
way back in the early days, 70s or even 60s, every one was running 4 speed manual trannys.
There used to be these classes such as modified production where the car was heavy, motor small, we are talking here some where around 270 cubes or less (cant remember for sure) small blocks. Destroked chevy 283 and such.
These cars would lanch hard, well in their day, 10000+ rpm. Well if you didnt break something from the motor on back, away you would go. ... to a blistering 10 sec or even high 9 second run.
The idea of the heavy flywheel or heavier than stock was to keep the rpms up when they dump the clutc, heavier flywheel at 10000 rpm will not cause the motor to bog down as much as a liter flywheel.
Road race guys were using the aluminm flywheels with steel inserts. They dont need to dump the clutch off the line like drag cars, but the idea was less flywheel wieght lets the motor rev up faster. coming out of corners and between shifts..
These days , depending on what you are running in drag racing, the cars are somewhat lighter, and the motors bigger than the old modified prodution days,,,(they were always a thrill to watch) The motors these days have more than enough tork, and with modern converters, I would go with the theory to keep it light to let the motor come up on the converter faster and recover between shifts.
I dont think you will gain anything by going to a heavier flywheel, probably lose some et, just my opinion.
It seems someone is always coming out with a new way to get some money from you.