Alright I have had this car for two months now...Its a great car... And I dont know if it is just me but I think something is wrong...When I floor it going straight it feels like the rear end is going its own way instead of straight. I have to correct it to keep it going straight...its hard to describe but it is weird..any ideas also the steering wheel make this annoying squeak when I turn to the left..how do I fix?

Have you had a BMW spec four wheel alignment (with the weights in the car) done?

No I have'nt had an alignment since owning the car..but my car is lowered and my wheels are 8.5 all around.. Its feels like the rear end is swaying from side to side under acceleration

All of the rear suspension components need to be inspected and replaced if worn, then the car needs a correct (per BMW specification) four wheel alignment. That should cure any handling problems.

Your rear trailing arm bushings need to be replaced. Worn out RTABs are very common and will lead to these exact symptoms. I would reccomend replacing them with an aftermarket urethane type.