Gutting an OEM Lib GT muffler for maximum airflow - 2009

by **Sentinel** » Sat Apr 04, 2009 8:17 pm

Nice work cpitts - looking forward to clips once you're able to!

Hats off to ya for having a go.

by **cpitts** » Sat Apr 04, 2009 9:19 pm

Cheers for all the props guys. Appreciate it after the many speculative comments on here.

The real validation of success/failure of this play session will be when it's stuck on a dyno with stock mufflers then I fit these ones and do back to back comparisons. That's not gunna be for a while though, that'll be when the full retune, etc gets done so that's a bit down the track.

by **Sentinel** » Sat Apr 04, 2009 9:30 pm

We'll hear it on the 13th??

by **cpitts** » Sun Apr 05, 2009 3:17 pm

Sadly no. Did a recce with Mr Blonde today though, I'm sure he'll be able to provide feedback with what it sounds like tho, even if I was following him the whole day. :lol:

by **Mr White** » Sun Apr 05, 2009 5:48 pm

Sounded sweet!

It certainly didn't sound like a 'burble', but was a lot deeper, but not droney AT ALL. . . oh and the crackle
at gear changes . . . nice!

It wasn't as loud as i expected cpitts, at idle i could barely hear it, but when you hit it it sounded aggresive.

I want to see and hear this car after it goes to AVO for a tune.

by **cpitts** » Sun Apr 05, 2009 7:27 pm

Yeah, funnily enough you can't hear much of that from the drivers seat. :lol:

Agree that it's almost silent at idle, even I was a bit surprised at HOW quiet it is idling.

Crackle is most likely a by-product of running rich. You can see that on the computer when you tap the accelerator and it quickly springs towards 50l/km :shock:

. That'll be fixed in a retune.

The running rich shows 2 things:
1. The engine is flowing a LOT more air (which means more power and that the mufflers are doing exactly their job)
2. The DBW is programmed to let the throttle be open a little bit longer than when you lift your foot (ie: overrun)

And yes, even in the drivers seat you can hear it open up when you push the pedal down, even partially down. :wink:

Guess it'll drown out the whistle from the intake :lol:

by **cpitts** » Mon Apr 06, 2009 9:59 pm

OK then.

MP3 can be found here:

http://www.corptech.no-ip.org/upload/2009-03-27%20Lib%20Muff%20Gutting/GTMuffler_gutted_1.5K_2K_4K.mp3

Excuse the link-speed, it's on my server at home.

Also, excuse the crap, crap noise in the background. Windy tonight and done in cold, dark so there's a bit of background junk. Also, being night, couldn't do any real rev tests.

Sample has:
- start, idle,
- 2 x 1500rpm blips of the throttle (then idle)
- 2000rpm blip (then idle)
- 4000rpm blip (then idle)

On a clear windless day I'll do a proper set of tests and ranges.

Not as rumbly as I'd hoped, but the gentle whistle of the turbo on the 4000rpm blip is as hoped. Nice clean air-path. :-)

by **Arith** » Mon Apr 06, 2009 11:20 pm

cpitts wrote:Agree that it's almost silent at idle, even I was a bit surprised at HOW quiet it is idling.

It shouldn't have any drone nor be that noisy, at least not ear shattering. There's still that humongous muffler sitting on the centre pipe reducing quite a bit of noise before it even reaches the mufflers.

by **cpitts** » Tue Apr 07, 2009 9:03 am

Arith wrote:
cpitts wrote:Agree that it's almost silent at idle, even I was a bit surprised at HOW quiet it is idling.

It shouldn't have any drone nor be that noisy, at least not ear shattering. There's still that humongous muffler sitting on the centre pipe reducing quite a bit of noise before it even reaches the mufflers.

Yep, tip size and length = drone. And that hasn't changed.

As for the muffler can, with the pipe in it and the few holes in it, it's a less of an influence than if I didn't put the pipe in.

by **smythie** » Tue Apr 07, 2009 9:25 am

I think Arith was referring to the centre resonator/muffler under the rear passenger seats

by **Arith** » Wed Apr 08, 2009 11:41 pm

smythie wrote:I think Arith was referring to the centre resonator/muffler under the rear passenger seats

Yeah, that's the one. Thanks Smythie. This is the monstrosity which is Subaru's definition of a 'resonator'

by **smythie** » Thu Apr 09, 2009 9:34 am

actually, that's more the driver seat isn't it

by **gtspec** » Thu Apr 09, 2009 9:48 am

smythie wrote:actually, that's more the driver seat isn't it

lets say the centre console just to be fair :lol:

by **cpitts** » Thu Apr 09, 2009 10:59 am

Arith wrote:Yeah, that's the one. Thanks Smythie. This is the monstrosity which is Subaru's definition of a 'resonator'

I do wonder a bit about that thing.

Maybe when I've finished with my other bits, I'll have a look (unless anyone wants to donate a spare of a MY07 GT-B for me to play with)

With all these Phat systems going on, there's gonna be a few lying around town. :lol:

by **GTSPECB STI** » Thu Apr 09, 2009 11:56 am

dont even bother trying to mod or gut that thing, just cut it out and put a resonator in its place.

Gutting an OEM Lib GT muffler for maximum airflow - 2009

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