OK, so I got these new strings in 10 Gauge: http://www.musiciansfriend.com/product/GHS-Dave-Mustaine-Signature-Guitar-String-Set?sku=103117&src=3SOSWXXA

And I have this guitar (and it has two springs for the Floyd):

And my question is:
Is necessary to add a third spring for Gauge 10 strings?
22 frets FTW!!!

Well I have a Godin Freeway Floyd and I use 10-52 ghs boomers - 3 springs.
So yes, I would definitely add another spring, you'll have alot more flexibility with string gauges and tunings in the future .