Noticed recently, only with window open, a noticeable whistle, starts just under 2000rpm and increase tll 3000ish, seemed worse when I was towing the other halfs horse box last week and when engines under it more strain.
Increases /decreases with engine revs.

It's into stealers next week before the warranty runs out. SHOULD there be any whistle before stealer says no issue ? ?

Drive Merc Ambos at work and we regularly get similar noise, usually they find splits in the induction hoses ......

Thoughts ? ?

Grommet in the floor pan where the steering column goes through

The whistle is the turbo and is quite normal, a characteristic of the car if you like,

...not sure fitting a grommet in the floor will help with the window open AD

Beats saying Wind The Window up

A feature - really ? ? Never had it that bad on any thr turbo car?

It depends how bad it is, of course, every single one I have driven has done it, I wouldn't go as far as to call it a 'feature' but it isn't something that can be stopped as far as I know.
My last car had a new turbo fitted at 75k miles and still did it, it wasn't changed for the noise it was a different issue.

Ideally before you go in you could do with trying another car and compare, do let us know how you get on