By quite a bit actually. My tiny .9s are something I've grown used to, but I feel more comfortable on thicker strings and I've heard there's a tonal advantage, so I'm moving back up to 11.

However, my Strat is set up for .9s, so what will I have to adjust with my new strings? I know the intonation will need re-set, which I can do, but I've heard I'll have to lower the trem arm too?

Thanks for the advice.
Call me Callum

Current gear - 06 MIM Strat, '02 Epiphone Les Paul, Peavey Rockingham, Tanglewood TF8, BLACKSTAR★ HT-5 Combo, EHX Holy Grail, Boss DS-1, Arion SFL-1

Newcastle (and Port Vale)
Lower trem arm? Never heard of that.

You will probably have to adjust the springs in the back cos the strings will exert more tension and pull the tremolo forward. It'll stick out abnormally.
I once went from 9's to 12's on a crappy strat, and to my surprise it didnt implode...
Inanamate objects hate me
A jump from 9 to 11 usually requires a tiny bit of trussrod tweaking to get the neck back straight.
The Laney Thread are big and clever. No exceptions.
You might have to also adjust the springs in the back if the trem is too wobbly.

And it would need a setup (intonation, truss rod)