What does the inside of an oem WRX muffler look like?

[RockStaRRR]

Originally Posted by cfvwtuner

I didnt know where else to put this, so it's here.
I was bored and wondered what the stock exhaust looked like on the inside.
With much fanfare:

cut out all the inside bits and put that bitch back on
you call call it a "Muffler" -Jesse James

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[hikeeba]

Originally Posted by hikeeba

I'll post pics for all the steps when I'm done. But I don't think I should post it here, as I think we have outgrown the 'Member's Car Gallery.' Should I post it in the Int & Ext Mods forum, or Factory 2.0L Powertrain forum? Please advise. Thanks!

Originally Posted by tooocool49723

neither. Keep posting in this thread.

Yea, ok. But I wanted to do a more concise beginning to end thread, and I wondered where to put it. we have sort of morphed this thread, and it really doesn't fit into this gallery anymore. Or does it? I don't know...

[hikeeba]

Thermoforming the cover for the hole I created on the top of the muzzler. Material used is 5/16" flame rated Kydex T.

Kayak/cargo straps to help in shaping...


Done


Indent in top helps with proper placement/alignment insuring tight fit.

[pezman04wrx]

Originally Posted by cfvwtuner

I've contemplated doing the same thing, but to an 05' muffler ... Everyones mentioning a "bottle" or "air whooshing" sound which makes sense if all the internals are simply cut out, but why not weld up a pipe from the inlet side to the outlet side ... Hence why I'd like to use an 05' muffler (or STi) ... The dual tip would be too much trouble unless you just went from the inlet to a single outlet ...

[the_colombian]

^ I've wanted to try that. I did cut all the piping and weld a 3" catback pipe to the stock sti muffler. The annoying noise at the shift got even worst. I had to ditch the catback. It had some rumble to it, but it just didnt sound right when you revved it.
Im just going to leave it as is.
I have a 3" electrical cut out to help me get those exhaust gasses out now.

[Gil]

easy.

[hikeeba]

Originally Posted by gil_ong81

easy.

Now you tell me!


...Will work on it more tonight...

[Gil]

damn. what are you cutting with?

[dvang]

when your done i wanna hear it im in souteast wisconsin

[hikeeba]

Originally Posted by gil_ong81

damn. what are you cutting with?

Well, i ran out of cutting wheels but wanted to continue the project, so I was trying to get in there with anything I had; sawsall, tin snips, hacksaw... Hense the jagged look. I now have more cutting wheels, but because of the opning size, I'm finding it more difficult to get tools inside the unit.

Originally Posted by dvang

when your done i wanna hear it im in souteast wisconsin

10-4, I'll let you know. I'm in Waukehsa. I'll work on it more this weekend, and hope to have it temporaily closed up by Sunday night. I'll probably wait until it warms up a little bit before I fit it to the car.

[hikeeba]

Not to cross-post... Well ok, I did post an update on my thread in another forum. But I haven't seen anyone here on the other thread, so I will update my progress here, too.

OEM Muffler Hack Stage 0.1 will be installed when i am done writing this. Some progress:

And then I lost two pics. I basically made the rectangular hole in the left tailpipe larger, I smoothed out some of the inside edges with a grinder, cleaned everything out the best I could, and temporarily sealed it up for the stage 0.1 test run.

Sealed up temporarily:

I have two rows of 1/4" closed-cell weatherstrip sealing the cover. It looks and sounds like it won't work, but the cover is on tight, so we'll see how it goes. Again, inlet pipe is gone, upper velocity stack thingie is gone, tailpipe sections are opened up but otherwise intact, and the two interior walls are intact.

I don't expect this configuration to sound too good. We shall see...

[Gil]

can't wait. are you going to upload a sound file??

is it too much to expect stock, stage 0.1, stage 0.2, etc??

[hikeeba]

I am back from test drive 0.1.1 . No exhaust leaks from the temporary, so that's good. However, after a hard, high rpm 7-8 minute drive, the top of the cover over the opening was starting to soften ever so slightly. I have thought about this possibility, and will install a counter measure when I go to Stage 0.2

General impressions:
Yep, it doesn't sound so stock anymore. The beat of the boxer 4 is definitely more clearly defined at idle. To my surprise, there was more of the lower frequencies present. The volume was slightly louder than stock, but no where near obnoxious - at all.

Driving. omgbuttdynosays20+hp!!1!! No, not really. If anything, throttle response seems ever so slightly faster, but this may just be a psyche effect.

Inside the car, one can definitely tell that something is different. I have the intake silencer removed, and the airbox lower drilled. This intake configuration, when coupled with the stock WRX axleback or STi axleback gives me more engine sound in the cockpit than exhaust sound. With the Stage 0.1 muffler hack, the sound difference between engine noise and exhaust noise was more balanced. At lower rpm, I still had more engine noise, but when the pedal went to the boards, sound levels evened out between front and rear. Still, nothing was loud or obnoxious - at least in the car it wasn't. Bottom line on Stage 0.1 hack from inside the car = a little lmore noticeable sound than the OEM and STi axleback, but not loud. Lower frequencies are more obvious. You sort of have to be paying attention to notice the difference.

Outside the car - Now, I was by myself, so I was a little limited as to what I could do. I noted above what I noticed at idle. I backed up to our closed garage door, leaving about 3-4 feet between the car and the door, left the driver's door open, and worked the throttle. A different sound, yes. Loud, no. It was a more raw, defined sound, but not raspy or crisp. BUT, and this is a big but, as noted by others who have done this sort of mod before, the CHIRP surfaced. This is a slight squeak sound, only prevalent when rpms are falling, and it only occurs somewhere between 2K-1K rpm. It's not loud, and it can only be heard outside the car. When inside the car with the windows up, you can't hear it. It isn't consistently the same amount of chirping, but when it happens, it is the same pitch. This only happens when I back off the gas completely, and let the Rs fall. If one does a controlled decent of Rs down to idle, the chirp does not happen.

So, there you go. I am going to take it to work like this tomorrow. I believe I am going to proceed to Stage 0.2, maybe this weekend, which will entail opening up the front inner wall a bit.

Regarding sound clips: I have a Recording Engineering degree (Bachelors), a 16-track digital recorder, and a bunch of mics. However, I do not have any mics that I want to expose to the elements at this time, and I am not going to set up my recording apparatus in the garage. I tried to use an old cassette recorder, and was going transfer that into the digital domain, but I could not get satisfactory results from the cheesy little tape recorder. I will put some futher thought into the recording situation over the next few days before going on to the next hack stage. If anyone locally has suitable recording gear and would be willing to meet somewhere, I'd be happy to do so.

[rally_on]

good idea!

[HTPerformance]

Wouldn't it be cheaper to just replace it?

[FWD WRX]

yea but what's the fun in that

[runwrxrun]

^^^ yea, what he said.

That's why when people get in trouble with the cops they run-- to make things fun.

J/p

[waktasz]

Originally Posted by HTPerformance

Wouldn't it be cheaper to just replace it?

What is cheaper than free?

[hikeeba]

Update - commute to work.

Well, things seem to have settled in very nicely... Or something... What I am experiencing today is quite different than what I had last night. Maybe it just needed a little heat to settle things down. Last night's test drive was short and hard. This morning's commute was easier on the gas and longer. I drove about 3/4 of the time without the radio on.

Once the car warmed up, I noticed a lower frequency rumble from the rear end. not obnoxious in the car, but more noticeable than what I heard last night. At one intersection I opened my door at the light, but I really couldn't get the full effect.

On the way to work, I don't think I got above 5500 Rs. When I arrived at work, I parked, left the car running, opened my door, and gave the throttle a few pokes. Hmmm... NO CHIRP! And there are more lower tones present than were there last night. I got out and listened to things at idle. Yea.. That sounds alright!

I went into the building and snagged a co-worker. I asked Aaron if he sould sit in my car and stab the gas a few times while I stood outside and listened. Wow... WOW! Da-yam! Once you get on the gas, it really sounds decent. No chirp, plenty of low-end sound, no air-rushing sound, no leaks from the temporary cover - just sweet boxer sound delivered in a calm, controlled manner. It is still not loud, but it is more noticeable than before. On the gas, the volume does not increase much at all. I switched spots with Aaron, and let him have a listen. As soon as I revved it up, a big grin appeared on his face. Another co-worker on his way into the building said, "Hey, what are you doing hopping up a station wagon?"

Yea, I'm happy with this. Quite happy. This configuration does not offer much as far as the cool burbling or after-firing sound, but I think I can live without that. It sounds decent, and I'm going to close it up permenantly when I get some time.

I wanted to see if I could get a better sound out of the stock unit, and I definitely believe I did. It's not loud or obnoxious, but it is different, and I maintain the stock look of the vehicle. The project was fun. All cutting - no welding. Woot!

[RaceComp Engineering]

I would like the see this done to a stock STI muffler.

ANybody else feel the same way ????????????????????????????

Myles

[hikeeba]

I also have an STi axleback, but I am a little hesitant at this time to cut it open. Once I have my OEM unit all sealed up and running well for a few months, I'll consider the STi hack.

Actually, I've already considered the STi hack. What made the WRX hack so easy was that someone already opened it up and posted the pic. with that pic, I knew exactly what I was getting into. The Sti is a different shape, but I can't imagine the internals to be much different than the 02-03 WRX can configuration. Actually, I wouldn't mind starting with a single-tip 04-05 unit. I imagine those are very similar to the STi internal layout, but with larger diameter piping.

Cutting things up and is fun! Putting things back together and seeing them work afterwards is fun and rewarding!

[ooberdoob]

ok, it's official, i'm hunting down an OE GT muffler and hacking it apart. i'll weld it back at school if i can.

[mrwrx2002]

an answer that we all wanted

[xplane]

Updates!!!

[xplane]

Oh come on update this!!