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2018 Forester2.5i Touring Manual
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Discussion Starter · #1 ·
I have a 2018 Subaru Forester 2.5i Touring and I would like to know the stock exhaust pipe sizes. I know the front half is larger than the second half. I live in a place that will not allow me to work on my car in the parking lot, I do not have access to a garage to use and I don't have a vernier caliper to measure it. I am assuming the front is 2-2.5" and the second half is around 1.5-2".

Please help if you can!





Thank you!
 

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2015 2.5i
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Update: I replaced the second half of the exhaust, custom built with stainless steel. The pipe before the resonator was around 2.5" and the pipe coming out of the resonator was around 1.5", huge restriction there.
Hey DieselBacon,

What muffler/resonator combo did you go with for your custom build?

Thanks

Dan
 

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2015 Forester Premium MT
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32 Posts
Update: I replaced the second half of the exhaust, custom built with stainless steel. The pipe before the resonator was around 2.5" and the pipe coming out of the resonator was around 1.5", huge restriction there.
post a vid
 

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2018 Forester2.5i Touring Manual
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Discussion Starter · #6 ·
I will be able to put the car on a hoist in a month or so, I could make a nice video then. I had the exhaust built by GT Custom Exhaust near Toronto. They removed the resonator and replaced the second half of the exhaust. I think they used a Flowmaster muffler... it is stamped "G Speed", 2.5" SS pipe with a 4" tip.
 

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2018 Forester2.5i Touring Manual
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Discussion Starter · #7 ·
I tried to upload a video and audio file to show the sound, but this site wouldn't allow it. Video was too large and it wouldn't allow a MP3 to be uploaded. Sorry, I tried... but it sounds awesome. Sounds deep and some crackles and pops when I left off the fuel.
 

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2015 Forester CVT
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694 Posts
Update: I replaced the second half of the exhaust, custom built with stainless steel. The pipe before the resonator was around 2.5" and the pipe coming out of the resonator was around 1.5", huge restriction there.
Actually, not so huge. Exhaust gas temperature cools considerably by the time it exits the resonator, so the same mass of gas can go through a smaller pipe with the same velocity because it is more dense. It's called "physics", which is a science.

GD
 

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2015 2.5i
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Actually, not so huge. Exhaust gas temperature cools considerably by the time it exits the resonator, so the same mass of gas can go through a smaller pipe with the same velocity because it is more dense. It's called "physics", which is a science.

GD
WOW! A real live physicist. I encourage you can crawl under your car once it's warm and experiment by touching your exhaust at the headers and then at the muffler to get us some qualitative data points on exhaust cooling and then report back. Very interested...
 

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I will be able to put the car on a hoist in a month or so, I could make a nice video then. I had the exhaust built by GT Custom Exhaust near Toronto. They removed the resonator and replaced the second half of the exhaust. I think they used a Flowmaster muffler... it is stamped "G Speed", 2.5" SS pipe with a 4" tip.
Thanks for the reply. I'm thinking of working on my exhaust when I'm back in Montana next week as a buddy of mine has a hoist in his home shop. To keep the wife happy I think I'm going to replace my the OEM cat with a high flow cat (mine has 67k miles on it), swap out the resonator for an aftermarket high flow, and do a low noise muffler after the axel. She won't go for droning/backfire exhaust on a daily driver. I want to do some customer headers at some point, but I need to read into it and work out the math. I suspect I'll need a tune to see real benefits, and fortunately, I think I've found someone to do one on a NA.
 

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2018 Forester 2.5i
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Thanks for the reply. I'm thinking of working on my exhaust when I'm back in Montana next week as a buddy of mine has a hoist in his home shop. To keep the wife happy I think I'm going to replace my the OEM cat with a high flow cat (mine has 67k miles on it), swap out the resonator for an aftermarket high flow, and do a low noise muffler after the axel. She won't go for droning/backfire exhaust on a daily driver. I want to do some customer headers at some point, but I need to read into it and work out the math. I suspect I'll need a tune to see real benefits, and fortunately, I think I've found someone to do one on a NA.
Mind sharing who is willing to tune a NA I have been looking but to no avail, also a guy who runs a business called "inferno fabrications" sells headers for the 2.5i, might be worth checking out
 

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2018 Forester2.5i Touring Manual
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Discussion Starter · #13 ·
What did this run you? I am thinking of doing the nameless 5 inch muffler for me but this looks like a better solution depending on price
I paid $500 everything included, parts & labor. I probably could of got a better price, but it was a small shop with some nice techs and I wanted to support them.
 

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I paid $500 everything included, parts & labor. I probably could of got a better price, but it was a small shop with some nice techs and I wanted to support them.
Was it stainless or aluminized?
 
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