jin108

Cutting out primary cats

14 posts in this topic

I want to get rid of the downpipe cats in my 335i and thinking of either pulling them off and gutting them out with a screwdriver or getting a shop to cut them out and weld a straightpipe in there.

Gutting them would be the cheap option but might not be optimal for airflow as the cavity is bigger than the rest of the pipe and could cause turbulence.

I had a shop quote me $290 to cut and weld and they said they would do it without removing the downpipes and weld a bung in for the oxy sensor. Has anyone had this done? Just wondering how they would get a clean weld on the top of the pipes as there is not a lot of room under there.

I know best option would be to buy aftermarket pipes but we dont have emissions testing here and removing the cats can be a wof fail but if the stock pipes are on there they would never know. Especially if they are just gutted out. 

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Plenty of us running aftermarket downpipes here and wofs are no issue. 

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Have had aftermarket downpipes on mine for over 4 years -no issues getting a WOF.... I'd look at the VRSF ones as its reasonably priced

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Thanks for the replies i can pull the pipes myself and gut the cats for free instead of paying $500 or more for downpipes. Getting the VRSF ones would be cleaner i know. 

Do you guys get CEL with the downpipes? I dont think MHD has an auto clear for it right? 

 

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Don't get the CEL lights with the appropriate stage2+ map on MHD , its deactivates the check on the map from memory

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Yes MHD simply turns off the check.

I've been wondering about doing this too. Would consider having stock cats gutted if it's much cheaper, but I'm not too keen to pull out the downpipe myself.

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Same here, would be a much cheaper option. Think i might explore it further when I have some free time. Depending how hard it is to get the downpipe off

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With regard to replacing the cats with aftermarket downpipes is it a straightforward car on jacks job or do you really need a hoist? 

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9 hours ago, Herbmiester said:

With regard to replacing the cats with aftermarket downpipes is it a straightforward car on jacks job or do you really need a hoist? 

um its super tight. I have done a lot of the mods myself but was a bit tough for me. Think you need to drop the steering rack

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Dudes, I've got a used pair of cat free downpipes if anyone's keen. Looking for $390. Was going to put them on TM but maybe I don't need to...

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I know this is an older thread but just installed a new FMIC and have the VRSF DPs ready to install.  I was planning on doing it myself but on looking underneath realised that the RHD cars make for a super tight fit so not so confident any more.  Can anyone recommend a mechanic to install?

I also have a spare brand new in box set of VRSF down pipes for the N54.  I would be happy to get $400 or exchange for experienced labour to install mine.

 

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10 hours ago, Matth5 said:

BM Workshop would probably do it. 

Thanks for the tip.  I've booked in.  Understandably they wont commit to how long it will take as they don't know what it will require but have suggested 8 hours of labour or in excess of $800.

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JTUNE will be able to do it also, $800 for FMIC and DP sounds about right. 

Doesn't hurt to ask them for a quote as well.

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