[twistedmunky]

Hi everyone,

I apologise for this potentially silly question about downpipes. I currently have the MPE and resonator delete on my F30 as well as a Stage 1 tune.

If I wanted to add a CATTED downpipe (catless is illegal here), what benefits would this have? And would there be any noticeable change in the exhaust tone/sound seeing as I already have a resonator delete?

Thanks everyone. Any help would be greatly appreciated!

[andino]

It'll be louder but not as loud or raspy as a catless DP. You'll be able to run stage 2 on it if you get an FMIC as well as it flows better than stock.

[mike@x-ph.com]

Originally Posted by twistedmunky

Hi everyone,

I apologise for this potentially silly question about downpipes. I currently have the MPE and resonator delete on my F30 as well as a Stage 1 tune.

If I wanted to add a CATTED downpipe (catless is illegal here), what benefits would this have? And would there be any noticeable change in the exhaust tone/sound seeing as I already have a resonator delete?

Thanks everyone. Any help would be greatly appreciated!

You'll get a deeper and more aggressive tone, its not obnoxious at all just a subtle sound upgrade

[twistedmunky]

Thanks for your advice guys! Purely from a sound perspective, do you think that it is worth installing the catless DP? As in, would be deeper and more aggressive tone be noticeable?

[johnung]

Originally Posted by twistedmunky

Thanks for your advice guys! Purely from a sound perspective, do you think that it is worth installing the catless DP? As in, would be deeper and more aggressive tone be noticeable?

I wouldn't go catless personally because I don't want the gasoline smell. You already have exhaust upgrades that give you a great sound. IMO only go to a catted downpipe if your intent is to move to a Stage2 tune. For sound enhancement a BootMod3 Stage1 tune gives you the control to customize your burble and pop setting to sound any way you want.

I've got a Fabspeed HJS catted downpipe, stock midpipe and axle-back M Performance Exhaust. I actually got tired of burbles and turned them off completely using BootMod3. Now I really enjoy hearing the exhaust sound when I step on the accelerator. Making noise braking at a red light wasn't my thing.

[twistedmunky]

Thanks again for the help everyone! Definitely some really good advice there and real food for thought.

[snipagang]

I still cannot figure out how people pass emissions with catted/catless DP. I am thinking of getting a DP but I do not think it is worth it if you have to switch back to stock before emissions testing every couple years (NJ resident). Is there a way to avoid the not ready code?

[DJSF3014]

Originally Posted by snipagang

I still cannot figure out how people pass emissions with catted/catless DP. I am thinking of getting a DP but I do not think it is worth it if you have to switch back to stock before emissions testing every couple years (NJ resident). Is there a way to avoid the not ready code?

Yes you get a catted down pipe that is guaranteed not to throw the code if not then a tune can make it not ready if your state allows one to be not ready which most do.

[snipagang]

Originally Posted by DJSF3014

Yes you get a catted down pipe that is guaranteed not to throw the code if not then a tune can make it not ready if your state allows one to be not ready which most do.

Okay, in that case I would want to find a DP which doesnt throw a code (does anyone know of any). Second, if i am trying to go stage 2 FMIC/DP I would probably use bootmod as the tune. As far as I know you won't pass emissions in NJ unless you have 1 or less not ready codes excluding Cats. That means I have to get a different tune (not bm3?)

[DJSF3014]

Originally Posted by snipagang

Okay, in that case I would want to find a DP which does throw a code (does anyone know of any). Second, if i am trying to go stage 2 FMIC/DP I would probably use bootmod as the tune. As far as I know you won't pass emissions in NJ unless you have 1 or less not ready codes excluding Cats. That means I have to get a different tune (not bm3?)

There might be other options but I went with the fabspeed one just because it's been proven to not and guaranteed but there might be others but gotta pay to play with that one.

[snipagang]

Originally Posted by DJSF3014

There might be other options but I went with the fabspeed one just because it's been proven to not and guaranteed but there might be others but gotta pay to play with that one.

Yeah my father had fabspeed equipment on his 996 porsche and the quality was super good, expensive though. Would the one you ended up with fit the 320i n20?

[DJSF3014]

Originally Posted by snipagang

Yeah my father had fabspeed equipment on his 996 porsche and the quality was super good, expensive though. Would the one you ended up with fit the 320i n20?

Uhh no idea you would have to go to their website and look for the one that fits I got an n55 so I don't think so.

[jyerelek]

Catted, MPE, and res delete is pretty loud. I used to have mpe and catless which was a tad bit louder. It was so raspy without the res and the catted downpipe that I elected to put the resonator back on. It cleaned it up very nicely but did take away from the overall sound and burbles.

[alohasurftoad]

AFAIK, there are no high flow cats available for N20 that will NOT cause CEL. whereas fabspeed, active autowerke and cg precision ds-1 are guaranteed not to cause a CEL for N55.

the only high flow cat for N20 that might not cause a CEL is AFE Twisted Steel, however it is using a low volume 400cpsi cat so i'm not sure how well it flows. unfortunately i have not seen anyone here that has one.

ADD...stone eddy and supersprint(metallic cat) may not cause CEL but cost $1600. i have not seen anyone here with either

there is an extremely remote possiblitly(but most likely not) that fabspeed could custom make one but you'd probably have to send them your oem downpipe and it would cost more than their N55 for being a one-off custom fabrication.

otherwise, just get a wagner with HJS cat(if available) or ER catted along with a flash tune to mitigate CEL.

[snipagang]

Originally Posted by alohasurftoad

AFAIK, there are no high flow cats available for N20 that will NOT cause CEL. whereas fabspeed, active autowerke and cg precision ds-1 are guaranteed not to cause a CEL for N55.

the only high flow cat for N20 that might not cause a CEL is AFE Twisted Steel, however it is using a low volume 400cpsi cat so i'm not sure how well it flows. unfortunately i have not seen anyone here that has one.

ADD...stone and supersprint(metallic cat) may not cause CEL but $1600.

there is an extremely remote possiblitly(but most likely not) that fabspeed could custom make one but you'd probably have to send them your oem downpipe and it would cost more than their N55 for being a one-off custom fabrication.

otherwise, just get a wagner with HJS cat(if available) or ER catted along with a flash tune to mitigate CEL.

Okay so if the N20/N26 downpipe upgrades cause cel and likely "not ready status" how are people supposed to pass emissions? In my state NJ you can't have not ready status for cat, but you can have 1 not ready status. Just not sure how to get to stage 2 without messing up emissions and failing inspection. BM3 tune doesnt help you to pass either.

[alohasurftoad]

Originally Posted by snipagang

Okay so if the N20/N26 downpipe upgrades cause cel and likely "not ready status" how are people supposed to pass emissions? In my state NJ you can't have not ready status for cat, but you can have 1 not ready status. Just not sure how to get to stage 2 without messing up emissions and failing inspection. BM3 tune doesnt help you to pass either.

i have no idea NJ laws and what "ready status" is. is it a sniffer test?

the catalyst is really nothing more than a filter. if it's sniffer then i would think you need 300cpsi and/or longer internal catalyst length. of course, this will compromise flow. or you need to swap back to oem catalyst prior to every test. idk.

[andino]

I've read some replies where those in other states (aka not CA) pass with a HFC and some o2 bung extenders. You can have your o2 in ready state then and not trigger CEL.

I'll just swap back my stock DP when it comes time to smog. That or do the usual turner route of paying someone to smog.

[snipagang]

Originally Posted by andino

I've read some replies where those in other states (aka not CA) pass with a HFC and some o2 bung extenders. You can have your o2 in ready state then and not trigger CEL.

I'll just swap back my stock DP when it comes time to smog. That or do the usual turner route of paying someone to smog.

I just hate the idea of having to swap back and forth between DPs because I dont feel confident I can do it myself and having to pay a mechanic to do it over and over could get annoying. I dont really know how this works in NJ i am hoping i can find “a guy”.