For upgrades on braking you can try 05-07 SS disk brake setup, they are about 1” larger diameter than stock cobalt. Be warned, you may need to go to 5 lug wheels.
For the suspension. Use a stock 05-07 cobalt SS FE5 suspension….shocks, struts, front 24mm SS Cobalt sway bar, and forged Aluminum lower control arms and new short end links. With new sway bar bushings. If you have ABS then the 5 lug wheel hubs should not be a problem….
It would be nice to know exactly what one is working with instead of just guessing and throwing a random lint of parts out that may or may not work on your car.
yet…
It’s very hard to go wrong with a FE5 suspension!
If you think you need even more and continuous breaking you can get a Bimbo break setup with even larger diameter rotors. It will force you to larger diameter wheels.