Should I top off my Jack Flash #5?

I'm in my second series of grows. My flower room has an approximate 7' ceiling. I vegged under Florescent lights, but now flowering under 400w HPS bulb. I started flowering 2 Jack Flash #5, that I had grown from seed, when they were both 10" about 15 days ago. They are both now right at 36" and looking extremely healthy.

I keep the light about 16-17" above the top of the plants, so I don't feel like they should be stretching. According to the Sensi Seed site, I still have another 40-55 days of flowering and the strain can reach heights of 5-6 ft. Obviously I don't have the space to grow them that tall. But I'm also wondering if they should be tapering off growing, or since it's more sativa dominant I can expect more heighth gains and should look into topping them off.

Here's a couple of quick pics of one of my girls. Any tips and advice are kindly appreciated!

how old are they,, better yet how long have they been fowering....

vegged for 30 days, and as mentioned they are 15 days into flowering. thanks,

oops sorry I got it now 15 days,,, they just might be done growing or maybe a little bit more but not much....

I would Bend them instead...it will up your yeild completley...

time for the buds to start forming..........

I was thinking about bending. But I currently have a Silver Haze that 55" bent over in my closet, along with a Super Skunk that's bush-like (both should be done flowering within 2 weeks, i hope). My closet is 7' tall and 7' wide, but only 3 ft wide. So I'll be running out of space quickly if I bend any more over I think.

Will topping it off significantly decrease my yield?

Its a little late in the game for topping but not too late,,, you will not get as much bud but if you need the room do it..............