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Discussion Starter · #1 ·
I was wondering does the H22 downpipe bolts to the H23 cat? Saturday afternoon the welds on my "custom" piece of pipe that connects the 5th gen downpipe to the cat decided to let go and I'm practically running open header. Since I now have a 4th gen H22 downpipe I was thinking about changing it now since I have to do some work under there anyway. So is it a simple bolt on or is there something I have to modify? I did a search but most of the stuff I found had to do with the H23 cat and a H22 catback.
 

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New Boeing Engineer
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This is in your 4th gen right. I know that my JDM H22 downpipe flange didn't match up with my H23 cat very well. All I had to do was elongate the holes in the H22 DP and they went together fine.

My question is, how did you get the 5th gen DP in there? Isn't it much shorter than the 4th gen DP?

HTH
 

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Discussion Starter · #3 ·
Zimmlude said:
This is in your 4th gen right. I know that my JDM H22 downpipe flange didn't match up with my H23 cat very well. All I had to do was elongate the holes in the H22 DP and they went together fine.
Well that's exactly what I'm gonna end up with. A JDM H22 downpipe and a H23 cat. If that's all I need to do it's not that bad.


My question is, how did you get the 5th gen DP in there? Isn't it much shorter than the 4th gen DP?
Yes it's about 8-10 inches shorter than the 4th gen DP so what we fabricated a small piece of pipe to connect them together with a flange made from a piece of metal about 1/4" thick. And it's the weld on that part that broke.
 

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Yeah, you should be fine. I just used an oxy-acetylene (sp?) torch and cut the holes. The ones on the H22 DP are further out from the center than the bolts on the H23 cat so the holes need to be elongated toward the center of the pipe.

Goos luck,
 

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I ended up buying a Carsound cat and a completely new VTEC exhaust system, but you could just waller out the holes on the DP to make it fit.
 

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Discussion Starter · #6 ·
Absolut said:
I ended up buying a Carsound cat and a completely new VTEC exhaust system, but you could just waller out the holes on the DP to make it fit.
We ended up just welding the pipe back together but I might get something else (header, cat, catback) next summer or so. Is it just me or the JDM flange has a weird angle compared to the cat?
 

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I've had the same problem with my flanges.

I have a '94 Si with the JDM H22a and the JDM DP flange is a lot bigger and beafier than my H23 cat flange.

I'm am going to have to make a new flange and/or buy an aftermarket (USDM) header. :(
 
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