^^ correct. lightweight flywheel just 'frees up' a few 'lost' whp...it's not a power mod so to speak. it just lessens the parasitic loss the stock flywheel has..and for the celica it's only a few whp, definately not 15-30.
look at it this way..the 2zz engine makes 180 bhp (thats AT the flywheel). a typical dyno will show you have about 160 whp (true horsepower with everything attached). so you're only 'losing' 20 horsepower through your a/c system, exhaust syste, transmission, etc. and so on. and some people think replacing just the flywheel will give you all of that back? not a chance. try 2-5 whp fained back and call it a day.