8cm vs 10cm is about preference.
8cm keeps more at lower RPMs and 10cm moves things to higher RPM.
All about what you want.
It doesn't matter if you're cammed or whatever, this will affect turbo performance similarly no matter what the rest of your setup is like. It will always have a similar trade-off. You'll get one guy saying cams are made for top end and 10cm is best, then another guy will chime in saying you need the 8cm to make up for the low end lost with cams. Whatever, there are valid arguments to go either way... bottom line is you just need to take your pick.