I loved my fidanza, the engine Revved much quicker but launches seemed a little tougher. Also if you do lots of DD make sure to get a street friendly clutch, my stage 3 sucked in the city. lolz
I bought the Ford Racing Steel flywheel for my DD and couldnt be happier. Its easyer to launch than the factory aluminum one , uses less rpm to get moving.
I just got a Fidanza, but if you have a stock car and stock clutch just get a billet steel and save some money. You aren't going to make your car gain 100hp from a flywheel so I would just get a steel if it is a DD. Otherwise the FRPP aluminum that comes in a 03 cobra is nice as well it just doesnt have a replaceable center section like the others recommended.
i am not planning to modify my engine or install a turbo or SC ... but i am planing to throw some bolt ons and use my car for occasional autocross, trackdays and streets of course. that is why i was thinking of aluminum flywheel