Gutting an OEM Lib GT muffler for maximum airflow - 2009

by **tangcla** » Thu Apr 02, 2009 8:32 pm

No, I meant, the trumper on the inside of the muffler, where the J-pipe was.

by **cpitts** » Thu Apr 02, 2009 8:40 pm

It's all gone now. It's now a stainless steel pipe from the inlet (inside the muff) to the outlet (inside muff) with a few holes drilled in it. :lol:

by **tangcla** » Thu Apr 02, 2009 8:46 pm

cpitts wrote:It's all gone now. It's now a stainless steel pipe from the inlet (inside the muff) to the outlet (inside muff) with a few holes drilled in it.

And no pics??

by **cpitts** » Thu Apr 02, 2009 9:23 pm

Sorry tangcla, it was all done by the eng firm yesterday/today while I was at work.

I'm almost 100% certain there'll be no internal shot of the setup. When I get them back though I'll take some flash shots into the outlet (inlet has a bend) to show as much as possible. I'd have liked an internal pic to, bit of a bugger, I hate mysteries! :evil:

by **tangcla** » Thu Apr 02, 2009 9:31 pm

cpitts wrote:Sorry tangcla, it was all done by the eng firm yesterday/today while I was at work. I'm almost 100% certain there'll be no internal shot of the setup. When I get them back though I'll take some flash shots into the outlet (inlet has a bend) to show as much as possible. I'd have liked an internal pic to, bit of a bugger, I hate mysteries!

Chop it up again, just to take photos, and weld it. :twisted:

by **cpitts** » Thu Apr 02, 2009 9:38 pm

There's the bloody problem! I can't weld!!! :lol:

by **smythie** » Thu Apr 02, 2009 9:40 pm

cpitts wrote:It's all gone now. It's now a stainless steel pipe from the inlet (inside the muff) to the outlet (inside muff) with a few holes drilled in it.

Very good. A big improvement on the separated inlet/outlet pipes IMO

by **moggy** » Fri Apr 03, 2009 3:00 pm

Jeez they look rough as bags inside, it looks like the sort of thing a backywater factory in China might knock out for $15 a set! Your mods would have to be an improvementon on the oem set. I wonder what the '07 GTb muffs look like inside? Will be interested to hear the sound clip. :good:

Bob.

by **cpitts** » Fri Apr 03, 2009 7:58 pm

Well, they're fitted!

At idle, they're quiet as stock but they throb subtly.

Give them some boot though and they open up pretty well :lol:

Results are:
- much smooth acceleration from as of 2200rpm to redline
- boost starts to climb as of 2200rpm (airbox is also modded remember)
- MUCH better v.low rpm driving (removes a lot of chugging/surging)
- some minor burble noise in the cabin, but certainly not intrusive (and this was with the radio off)
- Good all round improvements as expected

All up, I think it's WELL worth it if you want a completely invisible/stock solution.

Pics and MP3's to follow. Can't do MP3 tonight due to wind noise and don't think the neighbours will appreciate it.

by **cpitts** » Fri Apr 03, 2009 10:27 pm

And a few pics:

1. The back, note the welds where they added a bigger pipe to direct the air (didn't expect this)

2. The nice clean reseal of the mufflers.

3. The pipe as seen inside the rear muffler. You can see the small drill holes up the centre of the pipe.

All scars are invisible when the tips are on and back up under the car. That's the main thing.

by **AndySTi** » Fri Apr 03, 2009 10:30 pm

Niceness, looking forward to da sound clips

by **Hotwire** » Sat Apr 04, 2009 11:16 am

Out of interest - what has this cost you to get done? (the pipework and re-welding I mean)??

Also, are you going to get a dB reading?

by **cpitts** » Sat Apr 04, 2009 5:02 pm

Typically it's ~$50 per muffler 2nd hand
~$150 to weld the hole back up per muffler. (you can see the standard, it's not a backyard job)

The pipe was a trial run this time around and it cost WAY more than I was hoping. *cough* >$100/muffler *cough*

SO, the basic cut, gut and weld is an ~$150-200 per muffler exercise. (Yes, you may get a 2nd hand after-market item for around that but they won't look stock, really depends what look your after.

Lets just say, with this prototyping exercise, I could have brought Phat's mufflers and had an equivalent (or possibly higher) flowing solution for much the same $$'s.

After reviewing the overall exercise, I'd do the same again but not put in the joining pipe, that's where the excess cost came in. 2 VERY high flow mufflers for $400 is pretty damn cheap . . . . . and very sneaky.

by **AndySTi** » Sat Apr 04, 2009 6:13 pm

sound clips?

by **cpitts** » Sat Apr 04, 2009 7:42 pm

Sound clips coming. My mini-disc's battery has decided to give me a maximum of 4 seconds recording. :roll:

Tomorrow. I will say that the on the road improvement and smoothness of driving is exceptional. Exactly as expected and seen when i've done this to both my WRX's (and NA 2.5l Lib as well).

To give you an idea of the improvements:
- I can accelerate in 6th gear at 80kph smoothly and steadily to 110kph without any shudder or flooding feel.
- Driving in traffic at ~1500->1000rpm (peak traffic) I can let the car idle along in gear w/o ANY shudder or surging issues.

Oh, and it revs out real smoothly and easy now.

Sounds pretty nice too, not really sure how loud it is, but it doesn't scream or anything (not raspy either).

Gutting an OEM Lib GT muffler for maximum airflow - 2009

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