By the way...my mate also has a s2 and he had the same problem as you....oil coming from the dump valve...hate to tell you but his wasnt a turbo problem at all...he only got a new turbo...his wasnt really smokin either but after a while he got bad not major but bad enough..i thought his turbo was fucked to be honest but he decided to strip the engine to discover his engine was nackered....he got new pistons and a re-bore done....car is now back on the road and running sweet...