You don't need them unless you've got a big block engine. IMO it's just a waste of money on the 3.3 since the gears are already strong enough for big block power.
well, are you destroying the plastic ones? i wouldnt do a steel spur gear unless everything else was upgraded too, cuz with a steel spur you wont have anything to "give" when it needs too and you will destroy some expensive parts.
If you get the Picco and the tranny shells out.....replace the gears. I am not one to go replace everything first thing off the bat. No reason to. I have the 3.3 stock FOC transmission and so far it is holding up to the Picco Max just fine. When it shells out....I will upgrade. But not Until it goes out. You could drop $500 on upgrade just to find someting else is now the weak link. Play, have fun and fix it when it breaks.
I'm with Joey,no need to upgrade until it's proven necessary unless you have $$$ burning a hole in your pocket and just want to. Then why ask, just do it.