2.5 NA w/cat./straight pipe/muffler?

KelConquer · 10-06-2012, 10:30 AM

I've had plans on doing this for the passed week or so, I've searched Google and Nasioc and haven't been able to come up with any help. Probably just a stupid question, I'll admit that, I'm just not looking to damage my engine because the last thing I need right now is a new car

I'm looking to see what I'll get out of this before I do it. Now, I'm not looking for any hp increase or "amazing rumble". Over the passed few months my exhaust has been slowly acquiring holes randomly since it's the stock exhaust at 160k. It's becoming all rotted out and nasty.

Questions I have are:

Sound: What should I expect? I'm not looking for it to be any louder than an exhaust with a dime sized leak mid-way.

Size: I'm not sure what the exhaust size is on my 98 Legacy (limited). I can figure it out myself by dropping it (tried googling this aswell...) but if someone has the quick knowledge that'd be helpful.

Power: All I'm worried about concerning this is a loss in power (main concern is back pressure), my car suits my needs power-wise (when it doesn't have an exhaust leak...) so I'm not too worried about any gains. Although I wouldn't complain

Right now my exhaust consists of: Exhaust manifold, catalytic converter w/02 sensor, 2 additional catalytic converters, resonator, muffler. I'm looking to replace everything in bold with the stock sized straight pipe. Thanks for the help guys and again, my apologies if this is just a silly question. Every time I googled it was just people replacing their mufflers with straight pipe... meh.

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Counterfit · 10-06-2012, 12:44 PM

Back pressure is bad for power. Period. Removing the two cats will reduce back pressure somewhat, so basically long as you stay with stock sized pipe, you won't lose anything.

sfeather11 · 10-06-2012, 07:51 PM

FWIW - I just did something similar this past Wednesday to my 2003 n/a Baja. While I did install an ebay/Borla header, I kept (replaced) the 1st cat with a new stock unit, eliminated the 2nd and 3rd cat, along with the stock resonator. I replaced the stock muffler with a Magnaflow (part 14830), and used 2.25" piping from the cat back. While the sound is incredibly deep, growly, and just beastly, it is also ridiculously LOUD

. The droning inside the car is deafening, even at slow speeds. I am going to call the shop back on Monday and ask what the largest resonator (glasspack) I can add back in!

I did not notice any performance gains or losses with the reduced back pressure, and the car seems to run fine. I thought I may get a CEL from the increased flow through the cat, but nothing so far...

Peace!

KelConquer · 10-06-2012, 11:05 PM

I did a lot of work today, it's all hooked up but my muffler is about 3" passed where it needs to be so it's sitting on bricks right now. Started her up though and right away I could tell the air was flowing much better. Idle has a real nice sound to it. Since I have to shorten it a bit tomorrow it's not hooked up yet so I haven't driven it but we'll see how it does on the road tomorrow afternoon. If it turns out better than expected I'll post pictures/video, but it's just a boring ol N.A engine haha. Btw thanks for the input sfeather11, I'm using 2.25" as well so I'll be sure to let you know how I feel about the droning and overall sound! I'm glad that my exhaust will hopefully be maintenance free for a while now!

rotelmuffin · 10-24-2012, 11:53 PM

I did my whole exhaust on my 02 outback wagon similarly to the guy above me. Borla UEL headers, a single cat, 2.75" pipe and a magnaflow streets series muffler. I actually noticed some performance gains in terms of a widened power band, and it just ran better overall. The noise is great, and although it could be considered 'droning' at speed it doesn't bother me. FYI it did throw a CEL recently due to the increased flow, but I turned it off and it was no biggie. Good luck!

KelConquer · 10-25-2012, 04:35 PM

I believe I finished this the day after I posted this, unfortunately I put it all together before I thought to clear out all the honeycomb from my cat so it might get dropped again before winter to do that. But besides that it's running great and my lower end has definitely increased, I feel like it has a much "beefier" pull now. I only need it to last through the Winter so I used the cheap fit-together piping that U-clamps together from advance auto. Nice and quiet at idle with a nice "putter" to it. Cleared up my intake too (silencer removed) so I have a sound I'm pretty happy with now, for a N/A anyways :P

capitaWagon · 02-28-2013, 07:02 PM

Can you post a video? Same story with my car. I just ordered a muffler off of ebay and im looking to run a set up similar to yours.

10-06-2012, 10:30 AM	#1
KelConquer Scooby Newbie Member#: 321498 Join Date: May 2012 Chapter/Region: International Location: Syracuse, NY Vehicle: 1998 Legacy W. EJ25 Black	2.5 NA w/cat./straight pipe/muffler? I've had plans on doing this for the passed week or so, I've searched Google and Nasioc and haven't been able to come up with any help. Probably just a stupid question, I'll admit that, I'm just not looking to damage my engine because the last thing I need right now is a new car I'm looking to see what I'll get out of this before I do it. Now, I'm not looking for any hp increase or "amazing rumble". Over the passed few months my exhaust has been slowly acquiring holes randomly since it's the stock exhaust at 160k. It's becoming all rotted out and nasty. Questions I have are: Sound: What should I expect? I'm not looking for it to be any louder than an exhaust with a dime sized leak mid-way. Size: I'm not sure what the exhaust size is on my 98 Legacy (limited). I can figure it out myself by dropping it (tried googling this aswell...) but if someone has the quick knowledge that'd be helpful. Power: All I'm worried about concerning this is a loss in power (main concern is back pressure), my car suits my needs power-wise (when it doesn't have an exhaust leak...) so I'm not too worried about any gains. Although I wouldn't complain Right now my exhaust consists of: Exhaust manifold, catalytic converter w/02 sensor, 2 additional catalytic converters, resonator, muffler. I'm looking to replace everything in bold with the stock sized straight pipe. Thanks for the help guys and again, my apologies if this is just a silly question. Every time I googled it was just people replacing their mufflers with straight pipe... meh. * Registered users of the site do not see these ads. Last edited by KelConquer; 10-06-2012 at 10:48 AM.

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10-06-2012, 12:44 PM	#2
Counterfit Scooby Specialist Member#: 124254 Join Date: Aug 2006 Chapter/Region: NESIC Location: Rhode Island Vehicle: 2006 06 SGM Slowbaru "The Scoobinator"	Back pressure is bad for power. Period. Removing the two cats will reduce back pressure somewhat, so basically long as you stay with stock sized pipe, you won't lose anything.

10-06-2012, 07:51 PM	#3
sfeather11 Scooby Newbie Member#: 220466 Join Date: Aug 2009 Location: Landenberg, PA Vehicle: 2003 Baja Silverstone	FWIW - I just did something similar this past Wednesday to my 2003 n/a Baja. While I did install an ebay/Borla header, I kept (replaced) the 1st cat with a new stock unit, eliminated the 2nd and 3rd cat, along with the stock resonator. I replaced the stock muffler with a Magnaflow (part 14830), and used 2.25" piping from the cat back. While the sound is incredibly deep, growly, and just beastly, it is also ridiculously LOUD . The droning inside the car is deafening, even at slow speeds. I am going to call the shop back on Monday and ask what the largest resonator (glasspack) I can add back in! I did not notice any performance gains or losses with the reduced back pressure, and the car seems to run fine. I thought I may get a CEL from the increased flow through the cat, but nothing so far... Peace!

10-06-2012, 11:05 PM	#4
KelConquer Scooby Newbie Member#: 321498 Join Date: May 2012 Chapter/Region: International Location: Syracuse, NY Vehicle: 1998 Legacy W. EJ25 Black	I did a lot of work today, it's all hooked up but my muffler is about 3" passed where it needs to be so it's sitting on bricks right now. Started her up though and right away I could tell the air was flowing much better. Idle has a real nice sound to it. Since I have to shorten it a bit tomorrow it's not hooked up yet so I haven't driven it but we'll see how it does on the road tomorrow afternoon. If it turns out better than expected I'll post pictures/video, but it's just a boring ol N.A engine haha. Btw thanks for the input sfeather11, I'm using 2.25" as well so I'll be sure to let you know how I feel about the droning and overall sound! I'm glad that my exhaust will hopefully be maintenance free for a while now!

10-24-2012, 11:53 PM	#5
rotelmuffin Scooby Newbie Member#: 266556 Join Date: Dec 2010 Chapter/Region: NESIC Location: Boston MA Vehicle: 2002 Outback Wagon but not your moms outback	I did my whole exhaust on my 02 outback wagon similarly to the guy above me. Borla UEL headers, a single cat, 2.75" pipe and a magnaflow streets series muffler. I actually noticed some performance gains in terms of a widened power band, and it just ran better overall. The noise is great, and although it could be considered 'droning' at speed it doesn't bother me. FYI it did throw a CEL recently due to the increased flow, but I turned it off and it was no biggie. Good luck!

10-25-2012, 04:35 PM	#6
KelConquer Scooby Newbie Member#: 321498 Join Date: May 2012 Chapter/Region: International Location: Syracuse, NY Vehicle: 1998 Legacy W. EJ25 Black	I believe I finished this the day after I posted this, unfortunately I put it all together before I thought to clear out all the honeycomb from my cat so it might get dropped again before winter to do that. But besides that it's running great and my lower end has definitely increased, I feel like it has a much "beefier" pull now. I only need it to last through the Winter so I used the cheap fit-together piping that U-clamps together from advance auto. Nice and quiet at idle with a nice "putter" to it. Cleared up my intake too (silencer removed) so I have a sound I'm pretty happy with now, for a N/A anyways :P

02-28-2013, 07:02 PM	#7
capitaWagon Scooby Newbie Member#: 335478 Join Date: Oct 2012	Can you post a video? Same story with my car. I just ordered a muffler off of ebay and im looking to run a set up similar to yours.