td11pump

I have a 2006 Cobalt LT. The car drives great and has really given me no problems at all. I've had the steering column and sway bar bushing and links replaced by Chevy and that cured the clunking in the steering
I have changed the rims and when I did that I also changed the brake rotors and pads. I cleaned the hubs of all the rust (minimal) and put the new rims and tires on.
As I have read the torque value for the factory wheels is 100ft. lbs. I gunned the lug nuts on the first time and drove the car. VIBRATION when braking! I re torqued the wheels and the vibration lessened.
I see the newer Cobalt's have a 5 lug hub. I was wondering if I could do a direct swap and change the 4 bolt hubs to the 5 bolt hubs?
I know I'll have to get the front and rear hubs, new rims and new rotors and rear drums (Car needs new rear brakes I want to do this so that a slight difference in torque on the lug nuts will not cause the terrible vibration that I had.
The rotors were brand new when I put them on and they were also measured and checked on the rotor machine BEFORE I put them on. I have a friend who owns an auto parts store.
Any help with this would be great! Thanks!