Nobody ever said it was going to detonate on the spot.
It will just perform better, spool better and run quieter when it's assembly balanced. .
Garrett turbo engineer that used to peruse this site back in the day said in his opinion, that it should be assembly balanced.
It's a more professional way of doing things since your going to be pushing to the turbo beyond what the factory intended almost constantly with your upgrades, why not spend the few extra bucks and have it done?
Or just leave your stock wheel in place and go with the ATS housing instead? It widens the turbos range of operation a bit more than just the wheel alone, increases choke flow a bit, it's quieter than the WW and no disturbing of the turbo rotating assembly is required. /ubbthreads/images/graemlins/smile.gif