Hi guys just a quick question,I have a Subaru WRX 05 with full stainless exhaust from scoobyworld, including decat down pipe,and a remap from Andy carr, I've noticed that under high revs there's a fairly loud hissing sound, now I've had the car to three local garages (one a modified car enthusiast) now they've all said they can't see anything untoward, the WRX guy said that he's heard it before with Subaru's and it's because I've got a bigger exhaust and a remap and the car is a lot more free flowing and that this is causing the hissing sound ,does this sound like it could make sense to anyone and has anyone had this before,this is a similar sound to what I'm experiencing but I tend to be revving a lot more before it starts.any help would be appreciated.

Cheers

 

That sounds like the turbo spooling up to me bud only other way you would get a hissing noise would be a split intercooler hose or cracked intercooler 👍

Cheers.its definitely not the turbo spooling,that's a lot earlier on,I wish there was a decent knowledgeable mechanic around, maybe after the lock down I'll have to travel a bit,I'm based in Cumbria 😒 !Removed! end of nowhere.

It does sound like spooling or a boost leak , does it idle any different  ? lumpy or at higher revs

check the y pipe from the turbo outlet to the top mount intercooler and from intercooler to throttle body,  for cracks ,splits or leaks .

Does it still make and hold boost , if it's got a boost gauge what does it read ?

Has it got a standard recirc valve of aftermarket dump valve  and Is it sealing properly ?

Maybe get a smoke test done at any local garage ,to check for intake air leaks 

I've looked as much as I can and can't see anything obvious it has the standard recirculating valve on it also, I'll wait until th lockdown end's and try another garage although I know what they'll all  say"can't see out mate" 😔.