tent too crowded...

So I'm 4 weeks into flower, and my tent is way too crowded (Don't veg for 2 months if you don't have the space...). I thought about defoliating, but don't want to diminish yields.

Is there anything I can do? 4 plants under 1000w hps in a 4x4 ft tent.

Pics? Defoliate if it's early enough. Your probably going to get a nice yield if it's over crowded so it will be worth it in the end