[Dav340]

I'm looking at the VRSF B58 catless and high flow catted Downpipe. I dont think I will pass inspection with a catless downpipe but I still want that aggressive tone to my exhaust.

[TK335iMSPT]

Originally Posted by Dav340

I'm looking at the VRSF B58 catless and high flow catted Downpipe. I dont think I will pass inspection with a catless downpipe but I still want that aggressive tone to my exhaust.

Check with your states/local areas emissions and inspection regulations. There are only a few catted downpipes that will pass inspection. Fabspeed has a near perfect track record of being CEL free and passing emissions, Active auto works and CG Precision catted pipes also claim to be CEL free and pass emissions; but both are fairly new and don't have the same long term data Fabspeed does. All of these downpipes come at a cost though, as you will see when you look into them. If you have patience, you may be able to score one of these used. I was amazingly fortunate to score a used (500 mile) fabspeed catted pipe for 700 USD.

[alpinweiss340]

I got the catless because I was on a tight budget. Installing it myself was about 2hr (mainly because I only had a ramp and a second pair of hands would be better to help guide the DP into the flange) other than that, the only thing that bothers me is the spouse complaining about the smell after some spirited driving and then pulling up to a red light. (Oh yeah. Based in California too)
*i have taken it out one other time and installed it again, was a lot quicker doing it the second time around, I really don’t mind putting the factory DP back on for smog check
PS. Definitely invest in a pipe extender from amazon or something. It would have been even more of a task without it *for some reason the pic uploads upside down from what I’m seeing?

[Sleeper340i]

Started off with a high flow downpipe till the catalytic converter melted, ended up gutting it and went catless so I've experienced both.

If you're not going to go ham with the pops/burbles and want a more refined sound and less stink go high flow.

Catless definitely smells worse and can be smelled with window rolled down but I got used to it. Also has a louder/raspy sound but I feel like torque is increased and the louder sound has definitely grown on me. I'll pick catless any day over high flow now.

[mike@x-ph.com]

If legal, catted, in my opinion, is better

• Same performance
• deeper and more refined tone
• No fuel smell

[misguided_will]

not sure if this would be useful to anyone but i have the vrsf catted and after about 1000km it's throwing the P0420 code

[Uni-Rapide]

Originally Posted by mike@x-ph.com

• Same performance

I think it depends, as soon as you start running E-fuel, adding meth and/or bigger turbo you will get more performance from a catless downpipe.
Obviously in combination with a proper tune

[mike@x-ph.com]

Originally Posted by Uni-Rapide

I think it depends, as soon as you start running E-fuel, adding meth and/or bigger turbo you will get more performance from a catless downpipe.
Obviously in combination with a proper tune

Correct, catless will make more power once you are running a larger turbo. I should have made that clear

[Dav340]

Does anyone have videos of how the catted downpipe sounds also will I have to check engine light if I do catted downpipes ?

[BMWILUVU]

I've read posts on this forum on this topic and this is what I see.
For a catless downpipe, this will give you a CEL guaranteed. You need to clear the codes or have a tune do it for you. A possible solution is an O2 spacer though I have not heard of a catless 340 owner successfully using an O2 spacer.
For the 200 cell high-flow downpipes my preference is in order, CG Precision DS-1 then AA catted downpipe. Most 200 cell high-flow downpipes will give a CEL after X number of miles but I have only seen 2 owners of DS-1 who claimed they get CEL once in a while over many years. The sense is the AA downpipe seems to give a few more instances of CEL than DS-1 and has just recently arrived.
For 300 cell high-flow cats, the euro-compliant HJS catalysts used by Wagner and Fabspeed and HJS downpipes are very expensive and I have not heard anyone getting a CEL but at 300 cells per inch, the restriction is close to asking yourself why even bother.
I think the B58 stock downpipe has 2 catalysts 400 cell and I think the second is 600 cell but over 5" diameter sections where most downpipes are over 4" diameter sections some even 3".
I decided on catless.

[G.Newt]

Originally Posted by Dav340

Does anyone have videos of how the catted downpipe sounds also will I have to check engine light if I do catted downpipes ?

You have IG or social media? I can send you an exhaust clip. I'm running CG DS-1 5" catted + AWE catback. I don't have one of just the downpipe itself, unfortunately. This is a VERY aggressive combo, but no CELs (I've gotten it once, cleared, and hasn't come back since) and I'm emissions compliant.

[Skyhigh]

Originally Posted by BMWILUVU

For 300 cell high-flow cats, the euro-compliant HJS catalysts used by Wagner and Fabspeed and HJS downpipes are very expensive and I have not heard anyone getting a CEL but at 300 cells per inch, the restriction is close to asking yourself why even bother.

If you are asking yourself that for 300 cell, you must as well be asking it for the 200 cell.... the difference in backpressure / gas flow is minimal, see the diagram below. However one comes with an emission standard retention guarantee and type approval (and of course no CEL), the other - with a user manual how to cross fingers. After all, you get what you pay for....



There are a lot of threads related to Downpipes here.
I did my own research, whereas my priorities were (in that order):
- Performance increase
- Retention of the environmental standard of the car
- Quality and sustainability
- Sound improvement at the cost of minimal to moderate noise increase (I'll keep repeating this - "sound" and "noise" are 2 terms confused way too often...!)
- Price

I concluded I need to go for a HJS-based downpipe.

Dav340 Since your priorities may be different, my best advice is to simply search the forum and read the existing DP-related threads.... You will be able to draw your conclusions after that. Also don't forget that sound is dependent not only on the DP, but on your entire exhaust system. If you already have a sport exhaust system or parts of it or are planning to upgrade it, I would strongly advise you against catless.... you may very quickly end up in a very loud car with harsh and corrupted exhaust sound.
My experience is somewhat limited, but it confirms the advice @mike@x-ph.com gave you above.

[FirstBMWLA]

I recently went catless having already done dual resonator delete
I couldn't be happier.
sounds wicked on throttle and tame when not.
No drone.
Everyone's opinion is different but lots here seem to think it would be obnoxious.
Cold start is though. Tune with cold start noise reduction is kinda a must.

[dmanb2b]

Tune can suppress the check engine light, but you will still have that monitor in not-ready status. In NY you can't have more than 2 monitors in not ready status before trying to pass the OBD2 plugin test. Whether you pass the visual inspection depends on the shop/inspector and how picky they may be.

[Icy340]

Have you looked into CTS ? I have a CTS high flow catted downpipe with dual resonator delete. Has a great tone, not obnoxious. No cel because running bM3 Stg 2

[F30_Paul_]

Originally Posted by Icy340

Have you looked into CTS ? I have a CTS high flow catted downpipe with dual resonator delete. Has a great tone, not obnoxious. No cel because running bM3 Stg 2

Can you post a clip?

[Icy340]

Originally Posted by F30_Paul_

Can you post a clip?

quick vid before work ignore the shity edit & quality lol

[Dav340]

Anyone know which 02 sensor spacer I could try to help me pass inspection ?

[Jnat]

I started with high flow cts dp with a small spacer on secondary 02 and passed readiness.
I upgraded my turbo and went kiityless again with small spacer and again all readiness monitors are set. I have no explanation why but am very happy that this is the case...

[mike@x-ph.com]

Originally Posted by Jnat

I started with high flow cts dp with a small spacer on secondary 02 and passed readiness.
I upgraded my turbo and went kiityless again with small spacer and again all readiness monitors are set. I have no explanation why but am very happy that this is the case...

:thumbs-up:

Which downpipes did you go with?

[Cytoplasm0671]

Mike you've said in the past you prefer Active Autowerke over CG Precision. Any reason for that?

[BaconDouble]

I can vouch for the AA catted downpipe - I purchased from Mike at Extreme Power House.

While I had it professionally installed, I heard no gripes on the fitment from my mechanic and the sound/tone is much louder and deeper overall.
After almost a year and 10,000 miles, there is no check engine light (it is guaranteed to not throw any codes and it has not).

I didn't want to mess around with the smell or changing the downpipe every year for inspection time, so just wanted it done the right way from the start.
There is a slight smell, even with my catted DP that I attribute to the smaller 400 cell cat section itself (the smell is not from a leak, mine is not leaking) vs stock. I can't imagine no cat at all and how bad the smell must be.

There is no reason in my book why you shouldn't use a catted downpipe on your BMW, unless you have some type of dedicated race car and are trying to extract every HP you can. Absent that, prepare for complaints from your spouse, the kids, people next to you at a red light, etc. on the smell, not to mention trying to pass emissions every year. This isn't some type of Fast N Furious Honda with cat-less straight-piped exhaust, neon, chrome rims, and huge wing, I can have a fast car and keep it classy, nice rumble and speed when you punch it.

I am on BM3 Stage 2 93 octane tune with the AA catted downpipe and love it.