How do I know for sure that my Diverter Valve needs replacing?

[dadjokes]

I've had my Mk5 GTI for about 3 weeks, and I absolutely love it. But like any new car I'm just getting used to it, and coming from a Mk7 Fiesta ST it's a different car altogether.

I've got no proof that the DV has ever been changed, and as I don't know how the car should respond with a healthy one, I'm not sure if it needs replacing or not.

Car pulls hard after about 2500rpm, only noise I can hear is a high-pitched 'siren' like noise from driver's side footwell which I assume is the turbo spooling?

If the DV was leaking, would the car be totally flat?

[Octoparrot]

If it pulls like you say it sounds like it's fine. 

[pudding]

You normally get under boost fault codes if the tear in the DV is severe.

For the sake of 50 quid and an hour fiddling around on the turbo, I would replace it anyway for peace of mind.

[dadjokes]

Thanks all - got it replaced when the car was in for some other bits. Can't say it feels massively different, but just knowing it's sorted is good enough for me!