bigger buds!?

So i am checking out pictures and some people are getting huge buds. My plants are big and there are tons of flowers but they haven't really gotten big yet. I am in around day 40 or so of flowering and they are white widow. Will I see a huge gain in bud size in the next month? I am using 1 400w hps regular bulb.

Also I was thinking of ugrading to the 430w son agro bulb, will this help?

I don't know anything about that bulb but I can tell you a few things that I learned about flowering. The further along the plant is into flowering the slower it appears to grow. You should see a big improvement within the next 20 days but it'll be very gradual. Only in the beginning do the buds seem to grow quickly.