Custom X-Pipes

[donovan]

Originally Posted by leemik

If you are ever looking to easily resell the car down the road I wouldn't gut the cats.. it may cost you more in the long run.

Just put a test pipe on and put the cats away in your garage.. gutted cats create a little bit of turbulence anyway and aren't as ideally free flowing as a cheap set of test pipes.

just my opinion

--mike

That is an option, sounds like a good one, I can get the o2 extenders and o2 bungs and have them welded on the test pipe and just replace the second cats with resonators. I need to find someone who will sell me test connecting front pipes.

[erics02wrx]

So here are a few pics of the secondary cat gut / delete:

1. remove exhaust from car
2. cut slip joint at front of secondary cats, only cut through the outer pipe wall, not all the way through


3. this is what the cats look like


4. these are the tools needed

5. use the drill first to remove most of the catalyst material and then use the pipe to scrape and push out the left over material. You should have a pile of catalyst like this from the first one

this is what it should look like with the first one removed

6. now do the same for the next one and your pile of catalyst on the floor should look like this

7. now rig up a wire brush on a pipe and clean-up the inside


8. gut complete and ready to reassemble

9. realign and weld



10. clean up the welds

and this is what it should look like, once it gets a Little heat coloring on it the dealer will have no clue that it is modded!

[donovan]

I have no welder

[leemik]

Originally Posted by donovan

I have no welder

then you are out of luck as a DIY because the primary cats --> secondary cats --> x pipe --> resonator is all welded together as one piece... only the mufflers are detachable via slip on + clamps

[WCM3]

Originally Posted by BT M3

Yo Mike,

Yep I sold my E36, E46 M3 too. Primary cat removal keeps rear 200 cell cats so there is no stink andt he resonators so there is no rasp. Secondary deletes seem pointless to me unless you want to keep stock software. Primary cats are SERIOUSLY restrictive 400 cell and if i would guess 1.5" inlet cats.

You will need a proper tune that deletes the codes and sets readiness if you keep your secondary. Nothing works like the burger from the 80/81 DME's. So far so good with my tune.

BT

I like the idea of removing the primary cats, and I'll save some money over aftermarket x-pipes so I can invest in a tune. Care to give me more details about the "burger from 80/81 DMEs"? Still a newb to the e92 M3 lingo.

Originally Posted by erics02wrx

So here are a few pics of the secondary cat gut / delete:

Great work dude! Thanks for the step by step instructions. I'm assuming you just used a Mig to weld it? I have a Lincoln in the garage that should fit the bill perfectly.

[erics02wrx]

Great work dude! Thanks for the step by step instructions. I'm assuming you just used a Mig to weld it? I have a Lincoln in the garage that should fit the bill perfectly.[/QUOTE]

Yes sir, I have a small MIG that I used. The only thing to add to the instructions is that you will need to do a series of tack welds around the exhaust tubing as to not burn through, or set your welder to the lowest setting, very common for exhaust tubing.

I did this mod so that I would not have to deal with a CEL and then a tune, and the inevitable chance that the dealer will reflash the car while in for service. I would then lose my tune and have to pay for it to be reflashed to the ECU, its just not worth it to me for an extra 10-15 whp that a tune gives you. I will probably in time gut the main OEM cats also, I just need to find a good CEL fix that the dealer wont find. Most of the hp people are getting out of our cars are from the removal of the cats (20-30 whp) NOT THE TUNE! (10-15 whp). I drive my car hard at the track and I want to know that if something goes wrong with the car, the dealer will have less to complain about and no reason to say I voided my warranty.

[donovan]

Well damn the OEM exhaust haha, no worries I know a good shop that can help me out.

I just need to order connecting pipes and 2 resonators and I'll be happy. Nearly 500...

[WCM3]

Ok this is my plan. I'm going to replace the primary cats with some Magnaflow Metallic Spun cats. They are 300 cell (the same as Gintani) and should not throw a code. Maybe I'll try to incorporate the mechanical CEL fix just in case. Then I'm going to run a straight testpipe from those cats to the X-Pipe I listed earlier. Follow that with 2 vibrant resonators. I'm going to delete the secondary cats altogether. My car isn't going to have warranty work completed on it so I'm ok with not keeping it OEM look. What do you guys think about that setup? Should help with the responsiveness and add a little more growl.

http://www.summitracing.com/parts/MPE-59926/

[BT M3]

Originally Posted by WCM3

Ok this is my plan. I'm going to replace the primary cats with some Magnaflow Metallic Spun cats. They are 300 cell (the same as Gintani) and should not throw a code. Maybe I'll try to incorporate the mechanical CEL fix just in case. Then I'm going to run a straight testpipe from those cats to the X-Pipe I listed earlier. Follow that with 2 vibrant resonators. I'm going to delete the secondary cats altogether. My car isn't going to have warranty work completed on it so I'm ok with not keeping it OEM look. What do you guys think about that setup? Should help with the responsiveness and add a little more growl.

http://www.summitracing.com/parts/MPE-59926/

I don't believe that is the same as gintani cats. I believe they use HJS.

[WCM3]

Originally Posted by BT M3

I don't believe that is the same as gintani cats. I believe they use HJS.

I meant the cell #. People said that the OEM cats are 400 cell, and Gintani's are 300, which do not throw CELs.

[donovan]

WCM3 I dont see anything wrong with that bro....same way I want to go..

get rid of primaries and secondaries and add 2 resonators where secondary cats were.

Where can you buy the o2 extenders?

[WCM3]

Originally Posted by donovan

WCM3 I dont see anything wrong with that bro....same way I want to go..

get rid of primaries and secondaries and add 2 resonators where secondary cats were.

Where can you buy the o2 extenders?

I'll need to research what brand the OEM sensors are. I run Bosch o2 sensors on my E36 with my PLX wideband. Once I know the connector on it, it shouldn't be a problem finding extensions.

[erics02wrx]

Originally Posted by donovan

WCM3 I don't see anything wrong with that bro....same way I want to go..

get rid of primaries and secondaries and add 2 resonators where secondary cats were.

Where can you buy the o2 extenders?

Just strait pipe the exhaust were the secondary cats were, no need to add more resonators. The stock exhaust already has resonators in the xpipe. I would add a second set of resonators to the exhaust only if i were going to go catless. The high flow cats and the stock resonators will be just fine for reducing sound volume.

[donovan]

So the stock reso are good enough with HFC cats.

I guess it would be the same if one just got a test pipe from the headers down to the stock secondary cats then...

[alpina527]

I think you would struggle to replace the primary cats because of the flattened shape of them. The aftermarket cats are round and will foul the underside of the tunnel.

How about straight piping the front cats, then move the Lambda probes to before and after the secondary cats which are only 200 cell. The only issue that I can see is that they might not warm up as quick as the primaries.

[donovan]

A lot of the aftermarket systems , well all of them have the round aftermarket pipes.

I will just give it a shot soon. I will be in my garage making movies and sorting it out soon enough :P

[M3Alpine]

does anyone know if its possible to gut the primary cats with the shape of it ??

[donovan]

If one had a welder I can assure you I'd give it a try...

[Dave07997S]

Originally Posted by donovan

That is an option, sounds like a good one, I can get the o2 extenders and o2 bungs and have them welded on the test pipe and just replace the second cats with resonators. I need to find someone who will sell me test connecting front pipes.

I wouldn't bother extending the 02 sensors. The car will still kick off a CEL as the cats so far down stream they won't be hot enough and the rear 02 sensor will still be sending a hot signal.


Dave

[Dave07997S]

Originally Posted by BT M3

I don't believe that is the same as gintani cats. I believe they use HJS.

HJS cats are a 200cpi while Gintani uses a cat made for them at 300cpi.

Also, the reason why Gintani HFC Xpipes don't throw codes in addition to the 300cpi cats, is they moved the rear 02 sensor out of the exhaust stream by quite a bit putting the signal where it won't trigger a code.

Notice how they moved the rear 02 sensors.



Dave

[donovan]

Originally Posted by Dave07997S

HJS cats are a 200cpi while Gintani uses a cat made for them at 300cpi.

Also, the reason why Gintani HFC Xpipes don't throw codes in addition to the 300cpi cats, is they moved the rear 02 sensor out of the exhaust stream by quite a bit putting the signal where it won't trigger a code.

Notice how they moved the rear 02 sensors.



Dave

Very clever setup...

Also so Dave your saying the extenders wont work because of the exhaust temp being unusual in that certain spot so I wont get a reading...

So then we can keep the front cat(primary) and remove secondary no problem correct...as well as resonator?

[alpina527]

Does anyone actually know for sure if the cats restrict airflow?

The main pipe is approx 2.5" dia, the cats approx 4" dia.

A 4" HJS 200 cell cat will flow 85% which when stuck onto a full flowing 2.5" pipe shouldn't restrict it at all

How does the resonator work? Is it a straight pipe with wadding around a perforated tube? Or does the gas go around a series of baffles?