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Why do I keep losing power going uphill? Note the flow direction of the honeycomb (and the fact its "free" and making its way down the pipe). Twice this has happened on my EA81, I hate cats. Replace with 18" of straight pipe, done.

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Well... I Had that Problem Long time Ago... Found Restrictive Flow in the "Y" the Cat and Also inside the Muffler...

So I Changed the Whole Exhaust Pipes with 2" and Removed the Three Filters (the Cat, the "Y" and the Muffler) instead of Muffler my Subies got an Empty Can, but Filled with Fiberglass Noise & Heat isolating (industrial Grade) Compound, so it Won`t be a Fartcan...

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I live in a county that doesn't require smog, ie the sticks. :banana:The one time I had to pass was in Oregon.

Edited by Bugaru

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Yep - that's why I always gut them.

 

GD

 

I have the means to cut one open and gut it and weld it closed..

(I own a mig welder and a cutting wheel)

Is this the best way to do it??

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7Point62, sweet name,

If youre going to cut it open and gut it, remove the exhaust and do it from the top, so IF you do have to get an inspection it wont be noticed. Cutting and opening is the best way to make sure you got it all out.

 

As far as gas mileage goes, I don't know. I dont have a fuel gauge or a properly working odometer yet. GD would know.

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I guess technically it's called DEQ up there and it was back in 2005 when I had it inspected last. The hatch is a 1984.

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You might pick up a few MPG if the cat is clogged or broken and jamming the outlet of the chamber. If it's not then you won't gain a thing. I run about 75% on them having some sort of issue that I wouldn't have known about had I not opened them up. So I don't even bother trying to save them anymore. If I needed a cat for some reason (I don't smog my rigs) then I would buy an aftermarket cat off ebay for $60 and weld it into the mid-pipe. The stock 20 year old cat is too much of a gamble IMO. Better to open them and know where you stand.

 

I always cut about a 6" sqaure out of the cat on the top, gut the internals, then weld the flap back on. It's all hidden under the heat sheild and they weld real nice as they are stainless.

 

GD

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what are some signs that your cat or midpipe might be clogged, and what would be a good replacement so you dont loose backpressure.

 

and i dont want this to evolve into a backpressure debate.

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All the scavenging you need is done in the stock header - before any cats. The cats should flow as freely as possible.

 

If you think you might be down on mileage and can't find any other reasons - it's worth a look inside the cat. I picked up about 3 MPG when I opened up the cat on my '83 hatch. The contents were completely gone and the metal brackets and mesh screen were wadded up in the outlet. Bumped me up to 26 MPG from about 23 (engine has a low comp. cylinder).

 

GD

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If it rattles, cut it out. I've seen cat parts go all the way down the line, you might have some bits in there. After I get my welder back, all I will have on the exhaust is a muffler.

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