250 Low rumbling noise from what I can only assume is exhaust

I think my Meg 250 has a cracked exhaust manifold. Making an awful noise but drive/performance isn't affected. The noise is really low and rumbling, with quite a bit of vibration, and this is at idle-2k revs. Above 2k its not as bad, but obviously not right. I can still hear the turbo spooling up and it still feels punchy so I'm confident its nothing major with the engine/turbo.

Anyone heard of this before?

Had a look underneath and there's nothing hanging off, exhaust isn't loose, obviously can't see a lot from the top. Annoyingly can't do anything at Renault till Monday when hopefully they can diagnose!!

 

10/10 young man. It's being fixed tomorrow at SMC Renault Aldershot. As it's just out of warranty and a low mileage car, they've got Renault UK to contribute 50% as well.

 

Yeh they were really good actually considering I just dropped it off this morning without them knowing. Just a shame they didn't have a courtesy car!

 

I retract my statement about them being quite good - they ordered the wrong part so I'm without a car again for another day.