Flywheel is not lightened (not enough to make a difference anyway)...if there was a 7 lb flywheel in the MSP stock, there would be a huge drivability issue (have you ever driven a standard with a 7 lb flywheel)...the average driver would stall it regularly for the first week at least (until he/she learned how to drive it)...you would have a hard time launching smoothly with that flywheel at low rpms. I think the average driver wouldn't want to go any lighter than 12 lbs.
Not to mention that you would want to be sure that the flywheel is properly/safely lightened....if not, you could encounter a flywheel shattering on you, which could be very dangerous (especially if it happens at high rpms)....I would install a scattershield for your tranny if you decide to do that.
Lastly...from what everyone else says, protege trannys aren't meant for racing....soo, a lightened flywheel would probably lead to premature wear on the tranny.
I'm sure there are others out there who disagree with me, but this is just my personal opinion (along with a few facts).
Peace,
Jesse