Down pipe
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From: CA
Down pipe
I'm looking at the section of exhaust that seems to be considered a down pipe while searching online. The two inlet pipe from the catted manifold to the mid section containing the large resonators. I am pretty sure, but not totally sure about the interchangeability between the GS and IS for this piece. The reason I ask is because it seems to come up cheaper when searching for it under "IS". I can order one for the IS300 which I'm thinking will fit just fine and save some money. Can anyone verify this?
Lead Lap
Joined: May 2015
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From: Illinois
The stock Y pipe coming off of the header is a different length in the GS years (98-00 and 01-05) from what I researched 2 weeks ago as I was looking for headers but I would imagine that Y pipe would not be the same as the GS.
Have you looked into the Megan Racing mid pipe? I got mine for $150.
Attachment 504395
Have you looked into the Megan Racing mid pipe? I got mine for $150.
Attachment 504395
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From: CA
You mentioned you installed your headers and the down-pipe at different times. Im sure headers are an obvious performance increase, but how about the down pipe? Did you install it before the headers or after? I don't see this piece doing much on it's own, but I have my mind on a cat-back and that's where it would make more sense to do this piece since the available cat back systems don't include it. Unfortunately I can't have fun with headers because of California emissions. The manifold is such an easy swap, Id run those headers and swap the catted manifold in for smog checks. But You can even get headers shipped to California! That's how tight they have it locked down.
Lead Lap
Joined: May 2015
Posts: 449
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From: Illinois
I always feel bad for the true car people in CA but there is some ways around it like registering the vehicle in another state, putting everything back to stock when that time comes around or if you have connections depending on the people you know. For me I was changing a original bank 1 o2 sensor and the sensor was so bad and had a hard time coming out. It took the threads out with it when it was removed and this is why I got the IS300 headers. Once the headers were installed I had a slight exhaust leak in that y pipe that got louder so this is when I decided to get that piece Y pipe after I had the headers installed. From factory the Y pipe does have a 3rd cat on it but now since it is removed, it flows better with less restriction so it does help slightly.
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I'm at the point where I want to do headers and just do the catted exhaust swap when smog comes arround. Just to clarify, the "IS" headers will bolt up to the GS midpipe? None are advertised for the GS, but I'm pretty sure they are the same, the difference being in the IS midpipe length. I have he Megan midpipe on there now.
Lead Lap
Joined: May 2015
Posts: 449
Likes: 49
From: Illinois
I'm at the point where I want to do headers and just do the catted exhaust swap when smog comes arround. Just to clarify, the "IS" headers will bolt up to the GS midpipe? None are advertised for the GS, but I'm pretty sure they are the same, the difference being in the IS midpipe length. I have he Megan midpipe on there now.
https://www.ebay.com/itm/3-2-COATED-...1Is:rk:27:pf:0
The black paint came off after a few heat cycles which is what others complained about with this header but I am happy with it. Also reuse your OEM exhaust gaskets at the cylinder head as the quality in those are much better than the ones that come in the kit.
Attachment 504390
Last edited by shwalker07; Jan 30, 2019 at 10:23 AM.
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Thread Starter
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From: CA
Great, thanks! I do have the GS megan midpipe so I should be good. I'm also getting an safc2 or afc-neo and gonna get the car dialed in. With the intake, full exhaust, and a tune I think the car should wake up and feel a bit more powerful. I plan to wire in the tuner so its hidden and really ony have the easy header swap to do when smog time comes around.
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Great, thanks! I do have the GS megan midpipe so I should be good. I'm also getting an safc2 or afc-neo and gonna get the car dialed in. With the intake, full exhaust, and a tune I think the car should wake up and feel a bit more powerful. I plan to wire in the tuner so its hidden and really ony have the easy header swap to do when smog time comes around.
I have done the full Header/Midpipe/Cat-Back setup. It's slow. And loud.
Lead Lap
Joined: May 2015
Posts: 449
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From: Illinois
It's not going to be noticeable aside from placebo effect and noise(raspy, horrible sounding revs). Also you're wasting money with ANY piggyback style ecu because the factory ECM will continue to override everything you do in the long run. IS headers don't state being compatible with GS because of the Bank 2 Sensor 1 O2. It is against the firewall on the GS and you will need to have a new bung welded in a better location. Maybe this is different with *some* brands, but in my experience this has been the case.
I have done the full Header/Midpipe/Cat-Back setup. It's slow. And loud.
I have done the full Header/Midpipe/Cat-Back setup. It's slow. And loud.
That IS300 header on that ebay link fit perfect with all new Denso o2 sensors but that header is not really a name brand though. What cat-back are you running? I installed all 3 items at separate times and the header with mid pipe was a noticeable small increase in pickup but once the Tanabe Medalion cat-back was installed, I really noticed a difference in pick up then.
Driver School Candidate
Joined: Sep 2017
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From: Panama
So the header does not line up with the stock Mid pipe of the GS300???. How was the gas comsuption and sound? I am considering doing exactly what you did, bud I am not that sure about using the Megan Racing Mid pipe. I dont want to spend that much, plus I am a bit worried that it mith be to loud or to much gasoline smell. I have a 2003 GS300
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From: CA
It does fit, but just know they are cheap. You should know your way around customizing if needed. Shaving on the mount bracket is what I had to do. Some need to open up the bolt holes a little. And finessing the midpipe some. You might have to ditch the bracket that connects to the bell housing.
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