Decat Advice Pls

[Touring GP]

Hey Guys,

just need some help ,

I heard that the Cats on the 325i become blocked as a common fault ,making the fuel consumption rather high,

Question: has anyone had this issue? , if so does Decatting make a big difference to fuel consumption ?

 

[Bemused]

I have a 2004 325 and a while back, took the cats out. No complications or funny fiddling was required. I took them out because I felt the car was struggling to rev freely. Took them out and fitted a plain piece of exhaust pipe in their place. The sensors were not affected so the car carried on running nicely without doing any remapping or resetting of the ECU.
Now she seems to rev nice and freely and is very smooth. (Might be my imagination) Fuel consumption seems to have stayed pretty much the same at around 10,5l/100kms.

 

[andrewbuch]

Just do it, dont ask questions about it

 

[Bayn46]

The only painful part is which route to go for removing the cats from the headers i.e. can they be cut out and replaced with cat foolers, should you go with custom headers, if so, are the better or worse than the stock BMW headers.

 

[AcidBurn]

Just do it, dont ask questions about it

lol guess thats the best most straight forward answer you going to get hahaha

plan on doing mine as well

---

The only painful part is which route to go for removing the cats from the headers i.e. can they be cut out and replaced with cat foolers, should you go with custom headers, if so, are the better or worse than the stock BMW headers.

yeah im also trying to get an answer to this as i dont want to have to do software/tuning or what ever they call it as well

who you plan on using to do the decat for you

want to try and get a price from Evolution exhaust

 

[Bayn46]

who you plan on using to do the decat for you

I plan on using Powerflow. I've only heard good things from them - they did a complete system on a friends 325i and it's sounded pretty awesome. Performances wise, I'm not sure though.

Need to do shocks first, then I can buy the noisy bits :rollsmile:

 

[AcidBurn]

ok i got my answers thought id share here.

just called evolution for pricing to remove all 4 cats you looking at approx 3k for everything

sad news is he says i will have to live with a error code . Im not very happy with this

 

[Baron]

You shouldnt have to live with error codes, they can fit mini-cats or cat foolers to trick the ecu into thinking everything is a-okay down there.

 

[Epoc]

I had the cats removed under the gearbox and replaced with straight pipes but found it too 'tinny' for my liking after awhile. Revs up freely but fuel consumption did not change for me. So I decided to replace the pipes back with canister silencers. Now it is a lot quieter, too quiet now unfortunately, BUT I was told that if I remove the cats from the headers it would sound much better and deeper, closer to 330i sound??

Anyone had experience replacing with header cats and how it sounds?

 

[AcidBurn]

You shouldnt have to live with error codes, they can fit mini-cats or cat foolers to trick the ecu into thinking everything is a-okay down there.

I figured as much that there has to be away around this, you perhaps know who does these cat foolers/mini cats in Cape Town

 

[LPM320]

I am currently faced with a similar situation with my e46 325i. It is quite heavy on fuel (uses 12.5l/100km on the exact same route my e36 328i used to use 10.5l/100 km to do) and I do feel that it is being held back a tiny bit power wise. Different places have quoted me on different things. Some places say they will take apart each cat, remove the contents, and then rebaffle the empty space (expensive, but maintain the same exhaust note), while others say they will replace all the cats with pipe (manifold included, cheaper, but car will pick up a tinny exhaust note). I think with the e46 there are only sensors on the top of the manifolds, before all cats, so im hoping that I wont have to deal with any cat foolers or error codes?

 

[Luben]

I am currently faced with a similar situation with my e46 325i. It is quite heavy on fuel (uses 12.5l/100km on the exact same route my e36 328i used to use 10.5l/100 km to do) and I do feel that it is being held back a tiny bit power wise. Different places have quoted me on different things. Some places say they will take apart each cat, remove the contents, and then rebaffle the empty space (expensive, but maintain the same exhaust note), while others say they will replace all the cats with pipe (manifold included, cheaper, but car will pick up a tinny exhaust note). I think with the e46 there are only sensors on the top of the manifolds, before all cats, so im hoping that I wont have to deal with any cat foolers or error codes?

I didnot have an errors codes when mine was done.