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      10-23-2017, 09:52 AM   #1
R3dliner
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Can the x-pipe be removed without primary cats coming off

As the title states, does the X-pipe come off with the cats and muffler or can I just remove the xpipe alone?
Hard to tell if the primary cats and x-pipe separate. Thanks

Last edited by R3dliner; 10-23-2017 at 09:59 AM.
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      10-23-2017, 09:55 AM   #2
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The X-pipe and cats are the same section (center section).

The easiest way is to remove the center x-pipe and muffler at the same time.
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      10-23-2017, 09:59 AM   #3
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Quote:
Originally Posted by Jobe. View Post
The X-pipe and cats are the same section (center section).

The easiest way is to remove the center x-pipe and muffler at the same time.
so the xpipe and the primary cats are 1 piece?
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      10-23-2017, 10:07 AM   #4
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All one pipe. Remove trans cover, remove all but very front metal engine tray bolts, remove passenger side 02 sensor connection cover (2 10mm bolts), disconnect 02s and make sure wires are free to drop with the midpipe, undo the header to x pipe bolts (I use a flex head 10 mm 12 point wrench on the torx head bolts on the header side and a standard 14 mm socket on the nut side), disconnect the secondary 02 harnesses, undo the x-pipe supports on either side of the trans, undo the rear exhaust to x-pipe clamps and slide them back. When you are ready, undo the 4 bolts holding the x-pipe at the x, but be ready to support the x-pipe (have a friend or hang it with wires or bungy cords so it does not drop). Then push the rear exhaust back -- this will take some force -- to provide a little clearance to free the x-pipe ball ends from the rear exhaust sockets. Keep the x-pipe supported as you free the rear end. Don't let it drop -- just get it past the rear exhaust socket. Then pull and wiggle as needed to pull the front end off the headers and bring the x-pipe to the ground. One side header actually inserts slightly into the x-pipe, so it won't just drop when you undo the bolts. I actually push the bolt ends up so the threads don't catch in the flanges as I am puling the x-pipe off. I don't actually remove the bolts fully -- just push them up into the upper flange so they are out of the way.

Might take you a couple of hours your first time. I can do it in 30 minutes now that I have done it a few times.
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      10-23-2017, 10:24 AM   #5
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Quote:
Originally Posted by pbonsalb View Post
All one pipe. Remove trans cover, remove all but very front metal engine tray bolts, remove passenger side 02 sensor connection cover (2 10mm bolts), disconnect 02s and make sure wires are free to drop with the midpipe, undo the header to x pipe bolts (I use a flex head 10 mm 12 point wrench on the torx head bolts on the header side and a standard 14 mm socket on the nut side), disconnect the secondary 02 harnesses, undo the x-pipe supports on either side of the trans, undo the rear exhaust to x-pipe clamps and slide them back. When you are ready, undo the 4 bolts holding the x-pipe at the x, but be ready to support the x-pipe (have a friend or hang it with wires or bungy cords so it does not drop). Then push the rear exhaust back -- this will take some force -- to provide a little clearance to free the x-pipe ball ends from the rear exhaust sockets. Keep the x-pipe supported as you free the rear end. Don't let it drop -- just get it past the rear exhaust socket. Then pull and wiggle as needed to pull the front end off the headers and bring the x-pipe to the ground. One side header actually inserts slightly into the x-pipe, so it won't just drop when you undo the bolts. I actually push the bolt ends up so the threads don't catch in the flanges as I am puling the x-pipe off. I don't actually remove the bolts fully -- just push them up into the upper flange so they are out of the way.

Might take you a couple of hours your first time. I can do it in 30 minutes now that I have done it a few times.
Thanks. I just saw the turner diy as well.
Are there any xpipes that I can buy without cutting into it that still retains the secondary cats?

Do you know what the torque specs are to the 2 bolts holding the primary cats?
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      10-23-2017, 11:03 AM   #6
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xpipes are different than test pipes. i think you're confusing the two.
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      10-23-2017, 11:15 AM   #7
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Quote:
Originally Posted by roastbeef View Post
xpipes are different than test pipes. i think you're confusing the two.
I may have worded it wrong lol.
I'm in the market for test pipes but I would like to retain my secondary cats and don't want to weld on the test pipes if there is a straight kit out there.
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      10-23-2017, 11:45 AM   #8
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Quote:
Originally Posted by R3dliner View Post
Quote:
Originally Posted by roastbeef View Post
xpipes are different than test pipes. i think you're confusing the two.
I may have worded it wrong lol.
I'm in the market for test pipes but I would like to retain my secondary cats and don't want to weld on the test pipes if there is a straight kit out there.
Ok, got it. No, there is no kit that will bolt on and keep you secondary cats.

You will need to visit an exhaust shop to weld on flanges to make the test pipes and your primary cats interchangeable.
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      10-23-2017, 11:53 AM   #9
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Quote:
Originally Posted by roastbeef View Post
Ok, got it. No, there is no kit that will bolt on and keep you secondary cats.

You will need to visit an exhaust shop to weld on flanges to make the test pipes and your primary cats interchangeable.
Was worth a shot to ask. Thank you kind sir.
Do you happen to know the torque specs on primary cat bolts?
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      10-23-2017, 11:56 AM   #10
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There are aftermarket x-pipes that have secondary cats. They replace the entire x-pipe. Some of the x-pipe sellers offer them. Try macht schnell, AA, mastermind, and there are probably others I am not thinking of.
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      10-23-2017, 12:26 PM   #11
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Quote:
Originally Posted by R3dliner View Post
Quote:
Originally Posted by roastbeef View Post
Ok, got it. No, there is no kit that will bolt on and keep you secondary cats.

You will need to visit an exhaust shop to weld on flanges to make the test pipes and your primary cats interchangeable.
Was worth a shot to ask. Thank you kind sir.
Do you happen to know the torque specs on primary cat bolts?
No prob. I tighten mine to the TAF standard (tight as f**k) and call it good.
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      10-23-2017, 01:06 PM   #12
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Do you guys think I need to buy new bolts to the cat? car only has 35k on it.
I know my last car the bolts were rusted a snapped right off.
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      10-23-2017, 03:54 PM   #13
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My 08 M3 has 90k miles and is driven year round in NH, where they salt the roads in winter. I have had my x-pipe off half a dozen times. Still on all original bolts and nuts. I would replace the cone shaped fiber gaskets at the header to midpipe connection.
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      10-23-2017, 06:51 PM   #14
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Header gasket can be a PIA to remove. One of mine was molded on and would not budge so I left it alone. No issues.

Quote:
Originally Posted by pbonsalb View Post
My 08 M3 has 90k miles and is driven year round in NH, where they salt the roads in winter. I have had my x-pipe off half a dozen times. Still on all original bolts and nuts. I would replace the cone shaped fiber gaskets at the header to midpipe connection.
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      10-23-2017, 09:03 PM   #15
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Quote:
Originally Posted by R3dliner View Post
Do you guys think I need to buy new bolts to the cat? car only has 35k on it.
I know my last car the bolts were rusted a snapped right off.
in case you didn't know, they are torque star head bolts. the nut is just a regular hex nut. i used my impact driver with a 1/2 to 3/4 reducer and a closed end wrench and blasted the bolt off that way.
i have replaced my gasket before, but i had recently replaced it (my afe xpipe came with new gaskets). it wasn't terribly hard, maybe took ten extra minutes. the bolts are pretty beefy (Mmm Mmmmmm) and mine were in pretty good shape, so corrosion may not be an issue.

pro tip if you're going to replace them- get some of those safety goggles that seal to your face. the gasket is like a layered lead-like material that is very fine and flaky. if it gets in your eyes, you're going to have a bad time.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
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      10-24-2017, 09:25 AM   #16
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Quote:
Originally Posted by roastbeef View Post
in case you didn't know, they are torque star head bolts. the nut is just a regular hex nut. i used my impact driver with a 1/2 to 3/4 reducer and a closed end wrench and blasted the bolt off that way.
i have replaced my gasket before, but i had recently replaced it (my afe xpipe came with new gaskets). it wasn't terribly hard, maybe took ten extra minutes. the bolts are pretty beefy (Mmm Mmmmmm) and mine were in pretty good shape, so corrosion may not be an issue.

pro tip if you're going to replace them- get some of those safety goggles that seal to your face. the gasket is like a layered lead-like material that is very fine and flaky. if it gets in your eyes, you're going to have a bad time.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
Thanks for the safety goggles tip. I'm going to have fun testing my new Milwaukee impact gun.
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      10-24-2017, 10:50 AM   #17
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If the gasket is not on the header flange, it is probably stuck to the x-pipe flange. You should clean it off and that is where you might want the safety goggles. A wire brush on a drill or a hand brush or sand paper or a scraper might work. Debris will likely go down the x-pipe so put a shop vac on the end of it or stand it up so the debris comes out and does not clog the cat if you use the stock x-pipe in the future.
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