When accelerating hard out of a tight left hand turn I get like a buzzing/knocking feeling through the steering wheel, almost like the abs feeling you get on the brake pedal when it kicks in.
Under normal driving and turning I don't notice or hear anything.
Any ideas?

 

do you have DCCD or is it just a normal gearbox? Could be the power steering belt slipping it would give a juddery feel under load.

 

Just a normal 5 speed wrx.05

 

Sounds like a good call on the belt though.