I have had my car for about 6 months now and it has given me about 6000 miles of trouble-free motoring, still love it.

Did all of the preventative maintenance, 2 oil changes so far, all other oils and filters changed, including gearbox flush, blanked egrs, changed top hoses to silicone, and then put on a Quantum remap. I am really pleased with how it has ran so far.

Yesterday, out of the blue, I noticed a distinct hissing whistling sound coming from what seems like the right-hand side of the steering wheel (RHD), as in through the vent, at around 2000 rpm to 3000 rpm, and only when going uphill. It is a noise that increases with engine speed, and as I am concerned, have not tested if it continues above 3000 rpm. I turned off the AC and fan, thinking it might be fan related but it is still there.

There is no loss of power or any difference in the way the car drives, no black smoke, nor are there any codes that pop up in the GAP IID tool. The car has its original turbos as far as I know, although I do not have its history, and has done 95k miles.

What could it be?

I don't trust the main dealers out here to tell me, and there are only one or two indys who are far from me, so an informed opinion would be very much appreciated.

Sounds like a turbo boost pipe leak

How difficult is that to repair and is it likely to damage the turbo?

Have a good feel around the entirety of the chunky rubber hoses at the top of the engine bay. The two closest the front of the engine bay are the upper boost hoses. They're prone to splitting (you will need a good squeeze and finger to find a hole, if there is one, as it might not be obvious).

If both are ok, you can look at the lower boost hoses however, they're best seen from underneath.

A place to start however, as these are cheap fixes. 2015 Range Rover Autobiography 4.4 SDV8

If you can find someone able to smoke test the induction side, that will pinpoint any leak(s), it may be a split in one of the inlet manifolds which is not unknown.

It turned out to be a split in the driver's side intake manifold, so ordered both sides, hopefully, have them fitted next week.

I had that with mine, ground out the split & about 10mm either side with a Dremel, cleaned with an airline and applied adhesion promoter, applied a good blob of Araldite Metal adhesive, heated to 30 deg. C. for an hour with a low power radiant heater - so far (over a month, with enthusiastic driving and a high pressure smoke test) so good, I know I'll have to replace it (or them) at some point but as a stopgap, it's a cheap fix.