LCP

...but there is another siren; I call it the "motorcycle siren in the distance" (sounds like one of your passengers is whistling a police siren) also known as the tea-kettle whistle, that so far seems to be on a lot of cars (but not all -- and nearly always after chipping). There's also a very subtle spooling "whistling" that you should hear down around/under 2000rpms when the turbos spool up.

CatOne

NorCal. I'm the guy who will be grovelling at the back from mile 1 in Redding :-(

LosGatosS4

up until my first service at 5k, the only sound from my turbos was the subtle turbo whistle... immediately after that service I would hear a loud "police siren" after cold morning start ups and the engine was under load or if I got into the boost a bit. It would go away after a couple of minutes tho.

After a couple thousand miles I changed to Mobil1 0w-30 and no more "police siren" EVER. However, shortly after that, the whistle got a bit louder and now kinda sounds like a dentist drill. It starts with spool up around 1.8k rpm, fluctuates in pitch with turbo spool up, loudest around 2.5k rpm and pretty much goes away around 3k rpm. The loudness has remained consistant now, so I'm not too worried... (knock on wood).

Kinda sounds like my turbos got oil starved when cold, after the 5k service, wore the bearings a bit and now they are a bit more noisy. I dunno, weird :-/

LosGatosS4

dealer put in 5w-30 dino at 5k BTW

BaysideRS4

but I can't worry about it anymore