Just installed SPT intake and heat shield. Just wanting to ask anyone else that has one about pre shift hissing. Starting about 2200 rpm I hear a loud hissing while on the throttle and it is constant until I shift or let off the gas. Then when I shift I hear the bov, then no hissing in next gear until reaching 2200 rpm again, repeat for all gears. My concern is I am leaking boost presure pre shift. Also, say I am just cruzing the speed limit in 3rd gear, not ready to shift but sitting at about 3000 rpm I will hear the hissing constantly until I shift or let off the gas. Any feedback would be greatly appreciated. Maybe that is how it is suppost to sound. Just wanting to check.

thanks

 

I had mine installed, SPT intake and heatshield a month ago or so and that's how mine is too. I think it's supposed to be like that though. Hopefully others will chime in because when I got it, I looked her for anwer but didn't actually ask it.

 

I mean I really like the sound but I can see it getting old on long drives. 5th gear, cruzing about 70, on the throttle to keep the speed, and that loud hissing sound.... mile after mile... hour after hour....
we'll see....

 

first week or so, i turned down/off my stereo so i could hear it. after that first week, stereo's back on and i don't notice the hissing anymore.

not sure there is a resolution though. if there is, i'd be interested to know.

 

The hissing is normal. You are not on the throttle enough to create boost in the manifold, so the "bov" is partially open, so some of the intake charge is being recirculated back into the intake path. If you press the throttle a little further, the manifold will see more boost and close the valve all the way and it will be quiet. As soon as you let off the gas, the valve opens and Pssssshhh. That's just the way partial throttle is, the turbo is not spooled up enough to close the valve all the way.

That is why Subaru put that silly resonator on the intake, because the every day driver doesn't want that noise. I like it, although it does get annoying on the highway if you don't have the radio on.

 

Thanks a lot PghRedBean
That is exaclty the explanation I was looking for. I am the type that wants to know WHY more than JUST BECAUSE. Explanation was great. I do like the sound and today on the way to work, I had the radio on and didnt seem to be too bad. The piece looks really nice. And I figure it will be usefull for power gains on down the line. Also in regards to the sound... Someone else told me the colder the weather outside the louder it will be..... Its cold in Denver right now... Never thought I would say we have too much snow..... Nice in the mountains.. not nice in the city.....

Thanks again...