Hi one and all, i have recently noticed a kind of whistle/warble when planting my foot down under boost, this doesn't occur if not under load, standing still rev it and nothing, and it seems more frequent in Fourth & Fifth gears and only on high boost over 1 bar or more, anyone got any ideas what this may be??

 

Standing still it won't build any boost to speak of anyway. Only under load will it really start working the turbo. Can't really say about your turbo, but my VF35 is very noisy, much noisier than my TD04 was, and at first it was quite worrying. I just got used to it in the end - it's a loud whistling once you get over around 10psi and 4000 revs.

 

Sound pretty similar, the turbo is a VF28 standard as fitted to a P1, the strange thing is if i change down to accelerate it doesn't make the noise, it's only when i boot it in 4 or 5

 

Well full throttle in 4th and 5th gear is about the most load you'll ever put on the engine, hence why yours doesn't happen until then IMHO. I was convinced I had a boost leak or something for ages, but three different Subaru experts didn't mention it and when I asked, they said it was nothing to worry about, just the sound of the turbo working.

 

Check the dump valve. I had this noise and the standard dumper was staying open slightly. Subaru know about this and have modified it.