2nd grow 3 og kush 2 weeks from harvest! do they look okay?

I'm growing them in coco and b with boost
using two 600 watt lights with extractor fan and oscillating fan
on one of the plants the very top leaves are going purple but only the top leaves! and doesn't seem to be affecting there growth any ideas what it is?
theres roughly about 2 weeks left in flower
was told they bulk a lot in the last two weeks is that right?
how do they look?
thanks guys and girls I no I'm asking lot of questions but really would appreciate any feedback at all good or bad!

Color changing is normal. The plant uses all available reserves of nutrients in itself as it gets near the end of the life cycle.
Take a look at the trichomes and let that be your determiner for when to harvest - not some arbitrary schedule of "7 week strain." Also, you can harvest ripe flowers and leave unripe flowers to mature for several more weeks if you need to. I always harvest in batches over a couple or few weeks. The less mature flowers will ripen and fatten up.

My OGK does fatten up lots in late flower they look nice overall good job ......and the purple can be just the temp getting cool during lights out no worries

Nice! Thanks for the post; looks great!

I just started OGK. I don't have nearly the lights that you do though, so I don't expect as much.