Can someone tell me please if its worth replacing the stock dumpvalve with a thirdparty re-circ / bov.

Can you improve spool up time by using a third party dumpvalve or is best to stick with the stock one?

The DV does nothing at all to help spool up. It just releases the back pressure allowing the turbo to keep it's speed between gears so come on to boost faster when you get back on the throttle.

Personally i reckon it does make a difference, feel's that bit sharper. I think there are people who would disagree though.

Atmospheric ones mess up the fuelling when they vent making it run rich which is not good for the Cats, if you still have them ;)

Personally i'd say it's a bit of a waste of money as an only mod.