210 hp? thats a lot bro.. roughly 20 hp more than stock.. the extractor also changed ar bro? have u checked the camshaft? maybe performance chip? mine e36 325 manual also.. dynoed 220hp.. cracked my head figure out what has the previous owner done to the car.. because the owner said that he didn't touch the engine at all...just performance chip (around 12 hp gain) , and cone type air filter (2-3 hp)..other than that stock standard.. therefore the hp figures does not make sense at all...after sometimes i found out that possibly camshaft changed, not yet known the brand.. by changing exhaust back box and air filter should not gain around 20hp i suppose.. correct me if I'm wrong..