Well let me tell you from experince I have a 1971 240z with a killer engine setup and the lightend flywheel really helped a lot matter of a fact it revs almost to fast. But yesterday i put a fidanza 7.5 pound flywheel on my car which is a 2004 ceilca GTS. I cant even tell a diffence. The guy at fidanza told me that because the celica already has a lightweight flywheel it does not make a noticable diffence. But i would still recomend changing it out because it will probally help with other mods like a TRD
header and Intake
, and Exhaust.
One thing I think is a problem is the Electronic controlled throttle. I think it limits on how fast the engine gains velocity. I think in the future that there will piggy back computer to help override the ECT on our cars.
To make a long recomendation short I would recomend it if you drive your car hard, or if you plan to modify the engine with other mods. But this one mod will not make your car the quick F-1 reving engine you are looking for.