Hey,
I was looking to purchase another cat for my 98 1.8t for the purpose of hiding a test pipe inside it. I understand that the car would not pass inspection since ma has emissions testing. However, should the job not be incredibly tough or time consuming, i could switch it in time for inspection.
I did some searching but could not find how to remove the cat. if anyone has a write up or could explain it, that would be great.

Thanks

 

That seems like a waste of time. Get a Labree HFC if you are running GT2871r elim or smaller. You will be smog legal and have better exhaust flow. Plus, you can reuse the stock O2 sensors without issue and there is no need for a de-fouler. If you need a 3" outlet on your cat, call up Labree and talk to them about the possibility of a custom welded outlet.

 

If MA has sniffers and you wouldn't pass emissions, forcing you to replace the testpipe which you hid inside a cat with a real cat, why not just forgo the hiding and leave the test pipe on there, then swap them out for inspection? seems like it would be less of a PITA

 

i figure that if i hide it in the cat, then i can still use the o2 sensors no problem in their stock locations. i could also fill it with fiberglass and use it as a muffler. also then if for any reason, someone checks in my car, then i wont get don for the test pipe

 

im sorry to tell you, but you have no idea what your talking about.

a test pipe is a solid pipe with a flange on each end, its the same legnth as your stock cat and fits directly in its place. i suppose you could attach the heatshield from the stock cat around the test pipe, but theres no reason to do that. there are some test pipes with a heatshield that look like a cat, but anyone whos going to open your hood will be able to tell the difference. you can also just kock out all the 'stuff' inside your cat so its essentialy a test pipe, although that will mess up the laminar flow.

this wont allow you to use your o2 sensors if the pipe didnt already have bungs for them in the test pipe, and you will still have to use anti fowlers. the o2 sensors are in the exhaust flow not just screwed into the heatshield.

and you can fill your heatshield with all the fiberglass you want, its not going to be a muffler. i suggest reading on how a muffler works as i dont want to type all that out. you would have to put the fiberglass inside the test pipe, which wouldnt stay there very long, and defeat the purpose of the test pipe all together. and it would make a mess and trap heat inside the test pipe. which i guess isnt the worst thing in the world. but unnecessary none the less.

 

so you're trying to cover the test pipe with a cat?

 

it would not be a purchased test pipe, but one that i could custom make. if i were to place a 2.5" pipe through the center and fiberglass in the extra space around it, wouldn't it effectively be a glasspack?
since the exterior is a cat, nobody would know the difference.

 

lol, just buy a hfc and you won't ever have to worry again. even stock cats have good flow already.

 

ok thanks for all of your replies. what brands are good for hfc's

 

well a glasspack isnt a muffler. a glasspack barely reduces the exhaust sound, it will cut out the high frequency noise a little, but not much else. the only benifit of doing that would be to keep the heat inside the exhaust stream for higher velocity.

and il tell you, its going to be difficult to get the cat heatshield on a different pipe and have it look like a stock cat. you cant just replace the pipe thru the center because they are attached. you will have to cut it all apart and weld it back together around your test pipe. you will destroy your cat in the process and need to buy a new one for emissions test use

in all reality though, unless you are driving like a complete tool and have a ton of mods that are clearly illegal, no police will stop you and check under your hood, except at emissions time. i would just buy a $80 test pipe off ebay and call it a day. put some exhaust wrap around it if you would like.