Aftermarket Catted Downpipe?

[scheirere]

Is it worth swapping out the stock downpipe for an aftermarket unit that retains a cat? I use the car as a daily driver and don't want to deal with a catless downpipe. There are a few choices such as Cobb, AR Designs, CPe and Wagner that are available with high performance / race cats. I'm just concerned that it'll be money wasted. Anyone with experience with one of these?

[Allen@MOTIV]

Catted DPs do offer some performance benefits over the stock hardware and is emissions friendly. However, IMHO, it's not worth the price difference and the omnipresent risk of failure that catted DPs are known for.

My advice is to go catless and just swap them out when it comes time for emissions testing if they do a sniffer, or use a DP fix if it's just OBD2 based.

[135Pats]

Agreed.

Sooner or later, you WILL burn up HFCs in the downpipes. Skip 'em.

For emissions DPfix

For smoke/smell purposes secondary OE cats or similar

[siegester]

What DP fix do you guys recommend?

[135Pats]

Originally Posted by cjof2003

What DP fix do you guys recommend?

BMS DP Fix. There is only one.

[loesch]

Originally Posted by cjof2003

What DP fix do you guys recommend?

JB4!

[PeteA]

I've heard good things about AR design both catted and catless. I'm not sure if the BMS DP Fixes work for the N55, but I could be wrong on that one.

Both JB4 and Cobb have support for the code delete/suppress feature though.

[loesch]

There isn't a separate downpipe fix for the N55 engine. As i understand it, the functionality is included in the JB4 but it's not a true DP fix. It just clears the codes relating to O2 anomalies. Some State inspectors in the US, mine included, get confused when the emissions devices show a 'not ready' status so they don't know what to do and pass the car. I hope the same goes for Australia.

[PeteA]

We don't have yearly emissions tests here. Basically, if an authority thinks your car is too loud / smells like rotton eggs (when full catless) they can give you a yellow defect sticker (we call them a 'canary'). You then need to pass a sniffer / sound test to make sure they are within the limits.

Reality is, don't go WOT infront of one and turn off the engine if you are pulled over so they can't smell anything.

[Roland135i]

Sooner or later, you WILL burn up HFCs in the downpipes.

Can you explain this? I'm really interested in this.

I've been thinking about changing my oem cats to 200 cell sportcats. Just for more reliability. Keeping my tuning to stage 1 chip, ITG sportfilter in oem filterbox, sport cat and the oem performance exhaust

Why would the metal cat burn up faster than the stock ones, and why is powergain not worth the swap?

Thx