Just wondering if anybody has done an Intake silencer mod to the 04 WRX sti yet?
If so, could you here a little more whoosh and whine or is it best to leave it alone?
Also, does it void the warranty at all?

OUT.

I've never heard of it voiding the warranty. I dont see the harm in doing it but many don't think its worth it. With the regular WRX it lets you hear the turbo spool up better, but I dont know if the effects would be different for the STi. Probably not.

It will definitely let you hear the turbo and stock BOV alot more. I love what it did to my wrx and the intake for the STI is the same.

If you wanted to do a cheap yet worthwhile mod you could get one of these:

http://www.kaynzengineering.com/stealth.htm

I have one and it's worth more than I paid for it!

you can just take out your resonator box in the fender that allows you to hear everything too. and just put a flex pipe from the hole to the back of the foglight cover. that's what i did.

Watch out for water getting in your intake.

When I cut the snorkle out of my WRX, I left the part where it came into the airbox, with the bolt that goes through the inner fender intact.

I used some 3/4"x3/4" high density adhesive foam insulation around the box inlet, sealing out warm engine compartment air.

I removed the engine compartment scoop, and installed an RS plug in the hole.

This way, the only air entering the intake is cold, and high enough in the fender to eliminate water getting sucked in.

I will do the exact same thing when I get my STi in a year!

Originally posted by cuscosti
you can just take out your resonator box in the fender that allows you to hear everything too. and just put a flex pipe from the hole to the back of the foglight cover. that's what i did.

I just got an 04 last saturday. I'm at 550 miles on it so far. It seems that in the past two days that the turbo has gotten louder. I can hear the turbo with my radio off and I can hear the BOV as well. This is without the intake mod.

If in doubt about the airbox silencer, check out A G Bell's book "Forced Induction Performance Tuning" (Haynes Publish), read chapter titled "air inlet system", then you will understand why Subaru routes the intake air through it, not for any performance reason, but to satisfy customers that don't want to hear the turbo, or intake roar, or BOV dumping back into intake.....(like what kind of freak STi owner would be opposed to that??). Anyway, Bell did some pressure drop tests with a water manometer on the Subaru airbox (may have been Liberty B4 twin turbo or WRX), his numbers are startling! About 1.5psi drop just at air silencer (before filter) at 7000rpm.

You should cut the silencer/air intake box in 2 places. First cut the silencer off. Then cut off half of the "Y"- where the top screw is, but cut in front of the screw so you can screw the pipe back into the airbox. All you need is the half "Y" to mount back into your filter. To further explain again:

1. Cut the silencer off with a horizontal cut, so you have the "Y" looking top part left. This top "Y" part is where the air comes in (from the engine air intake scoop) and then it goes to the filter.

2. You then make another cut to cut off one side of the "Y" where the air comes in from the engine air intake scoop. You cut in front of the screw, because you want to keep the screw so you can mount the other side of the "Y" to the filter box.

3. Then you take off the air intake scoop, because you don't need that anymore. And you tape up all the holes in your engine compartment which leads to the fender.

Now all you have is cold air coming from your fender, and not your engine. And you can hear the blow off valve and turbo. It sounds awesome. While racing, you can actually take off the fog light cover so a lot of air can flow freely. Even though there is enough air with the cover on. By the way, to take off the silencer's bottom screw, it's easier to go in from the fog light cover.

Sorry I don't have any pics.

PS. to make the cuts you can use a regular saw for cutting trees or something.

Originally posted by jimr
If in doubt about the airbox silencer, check out A G Bell's book "Forced Induction Performance Tuning" (Haynes Publish), read chapter titled "air inlet system", then you will understand why Subaru routes the intake air through it, not for any performance reason, but to satisfy customers that don't want to hear the turbo, or intake roar, or BOV dumping back into intake.....(like what kind of freak STi owner would be opposed to that??). Anyway, Bell did some pressure drop tests with a water manometer on the Subaru airbox (may have been Liberty B4 twin turbo or WRX), his numbers are startling! About 1.5psi drop just at air silencer (before filter) at 7000rpm.


Ummm, yeah... that's not a flaw in the design. When you rev an engine higher, it pulls more air through the intake tract. This results in more vacuum being created, which is where that pressure drop comes from. Nothing more, nothing less.