Suspension What might be my issue with stability?

I bought a 07 GT replaced the entire suspension Control arms, Bushings, Ball Joints. OEM sway bar bushings and installed Poly. and even installed KONI STR.T performance struts and shocks and a alignment, new tires and Callahan drilled slotted rotor with ceramic pads..

Now what I feel I have not felt with my 07 focus mainly because it is a front wheel can and lighter..

so what is happening is..

When I am say doing 70+mph and brake hard, but no locking up and I feel the ass of the car wanting to come high and it dives and a sway...
I would consider it aggressive driving..

So a for instance... going down expressway 80 mph then go on to a off ramp, tires are not sliding and feel good, grip is fine, but if I am on the brakes feels like its sways/dives a bit..

Now only thing I can think of is Upgrade to race springs.. lower car 1.5" and get a better sway bar set or do I need to get use to this at them speeds?

OEM, nothing right now has been upgraded except for the shocks. was hoping to keep the stock ride height because I'm a little tall myself and not the best back. if I make the car low it may hurt my back even more. but I should be able to get some good stability even with the stock ride height better than what I have now. I was thinking of getting myself some sway bars and some supports. but playing with the Ford Focus for the last few years I've never heard of the part that was recommended for the panhard. going to need to do some research on that part. it does sound like that might help.