To stink or not to stink? - Catless Downpipes

[SHONuf]

Hey guys long time lurker, and first time poster.  I plan on doing a proper introduction in the New Member Introduction, but for now I would greatly appreciate some insight into a downpipes question that I've been mulling over for a couple of weeks.  I've tried to do as much research as possible but it's not getting me any definitive answers.  After getting all standard intro mods completed on my '10 SHO (intake, plugs, t-stat, mycal, map sensor) out of the way, I've now turned my eye towards getting some new downpipes.  The thing that is really nagging at me is whether or not a set of catless downpipes will give the car that nasty uncatalyzed exhaust smell.  Bear in mind that these would be attached to the completely stock catback, so the 3rd cat would still be retained at this point.  When it comes time to upgrade the catback, I've got a very talented fabrication shop here in town that will integrate new high flow cats into the catback.  But I digress, that's down the road.  So to sum up

To all the guys running catless downpipes on a stock catback (e.g. retaining the 3rd cat), have you noticed any significant stink as a result? Is the single 3rd cat enough to prevent the exhaust from smelling like a Victorian England coal factory?

Thanks so much for reading, I'd really appreciate any insight from the guys that have run this!

[AJP turbo]

I had catless down pipes on a stock exhaust...i could tell a very slight difference in smell but not much...i would say you may not even notice....i loved the sound of catless pipes and stock exhaust

[SHONuf]

Ah I see.  So it's really not too bad at all?  My previous turbo Miata didn't run a cat at all and the stink was terrible.  I imagine half of that has to do with the fact that Miata's are about as air tight as ....I can't think of anything clever, but they're bad even with a hardtop to help seal them up.  Did you notice the mild smell while sitting in stop and go traffic or on the highway?

All the sound clips that I've seen with catless dp's sound great.  Nice mild growl.  AJP did you notice any drone issues that most people report once they ditch the stock catback?  I figure with the 3rd cat, resonator and two mufflers in place then it shouldn't be too droney especially on the highway but I can't say for sure.

[AJP turbo]

I noticed the smell when i stood behind the car at cold start when the 3rd cat didnt have any heat

I a little buzziness at high rpm wot but that didnt bother me and the start up idle actually had a little growl...id say mo drone since all the resonators and mufflers and 3rd cat were all still there

Unlike most people here i hate the sound of these engines with a cat back...i believe most people force themselves to like the new sound because they just dropped a grand on pipes

Going catless for me made the exhaust have the same tone just a bit louder

I wont be putting an exhaust on my 2.7 ecoboost truck either becuase it sounds like the 3.5....i will probably go catless on that too

[SHONuf]

I definitely agree there.  The only solution I've seen to the nasty harsh buzz/rasp we get when adding any catback is to rethink the exhaust all together.  I've heard a couple that run the downpipes into a Y-pipe and just run a single exhaust all the way back until it splits into dual mufflers.  I can't claim to be any expert on the fluid dynamics of it or why this so significantly changes the sound, but it seems significant.  If I ever end up getting a cat back, I plan on going that route.


So from what I understand, the smell that you might experience when the 3rd cat is cold is really only noticeable when outside the car, but it doesn't penetrate into the interior?  Does it tend to fade once the cat is up to operating temp?

[sholxgt]

I definitely agree there.  The only solution I've seen to the nasty harsh buzz/rasp we get when adding any catback is to rethink the exhaust all together.  I've heard a couple that run the downpipes into a Y-pipe and just run a single exhaust all the way back until it splits into dual mufflers.  I can't claim to be any expert on the fluid dynamics of it or why this so significantly changes the sound, but it seems significant.  If I ever end up getting a cat back, I plan on going that route.


So from what I understand, the smell that you might experience when the 3rd cat is cold is really only noticeable when outside the car, but it doesn't penetrate into the interior?  Does it tend to fade once the cat is up to operating temp?

I agree with AJP on the sound of these cars with aftermarket exhaust, but think that you're right about running a dual/single/dual setup also.  The original SHO's have that set up and can sound pretty good.

To my ear, the Magnaflow cat back sounds the best for these cars, but still probably not as good as stock.

Regarding the downpipes...I would either go catless or go with PPE catted.  None of the others really do much in the way of cleaning up the exhaust as they are outside of the threshold requirements for the ECU and you'll get a CEL with them.  I went with PPE catted only because my car is under warranty and I want to be able to take the car in with the factory tune and no CEL.  Glad I did since my car has been in plenty of times now and is being driven with the factory tune daily without a CEL.

If I didn't have a warranty and planned on leaving it tuned, I'd go catless.  Slightly more power and a LOT less expensive.

[StealBlueSho]

I definitely agree there.  The only solution I've seen to the nasty harsh buzz/rasp we get when adding any catback is to rethink the exhaust all together.  I've heard a couple that run the downpipes into a Y-pipe and just run a single exhaust all the way back until it splits into dual mufflers.  I can't claim to be any expert on the fluid dynamics of it or why this so significantly changes the sound, but it seems significant.  If I ever end up getting a cat back, I plan on going that route.


So from what I understand, the smell that you might experience when the 3rd cat is cold is really only noticeable when outside the car, but it doesn't penetrate into the interior?  Does it tend to fade once the cat is up to operating temp?

Regarding the downpipes...I would either go catless or go with PPE catted.  None of the others really do much in the way of cleaning up the exhaust as they are outside of the threshold requirements for the ECU and you'll get a CEL with them.  I went with PPE catted only because my car is under warranty and I want to be able to take the car in with the factory tune and no CEL.  Glad I did since my car has been in plenty of times now and is being driven with the factory tune daily without a CEL.

I agree with this... I have the stainless works catted downpipes and they trip the CEL... completely worthless if I need to actually pass more than a visual inspection....

[SHONuf]

Wow I had no idea that people were even having inefficiency issues with some of the off-the-shelf catted downpipes.  Well if I wasn't sold before, I definitely am now.

You guys were a huge help, I really appreciate the replies.  Can't wait to get my hands on the new downpipes now 

[ZSHO]

I always like to read reviews prior to purchasing a product and here' a review and answer straight from the horses mouth on SW Catted DP. Are your downpipes for my 2010 SHO legal in Arizona?
Asked by: Bill - 6/16/2016
Customer AnswerThese downpipes will not pass emissions testing in Arizona, even the high-flow catted variants. The custom tuning that's required with these downpipes usually involves disabling the O2 sensors to avoid a CEL, and Arizona tests for O2 readiness, as well as for emissions-related CELs.
Was this answer helpful?   YES  NO 2 of 2 Customer(s) found this Answer helpful.
Answer provided by:  Jason@Stage3 (6/16/2016) http://www.stage3motorsports.com/TA10ECODP-2010-2013-Taurus-SHO-3-5L-EcoBoost-Stainless-Works-Downpipes.html   BTW have my own personal opinion on these so called catted DP but rather not go there. Z

[StealBlueSho]

ZSHO were you the one that got SW DPs and the O2 bung was on the wrong side of the pipe?

[ZSHO]

ZSHO were you the one that got SW DPs and the O2 bung was on the wrong side of the pipe?

YUP......few years back.had to pay installer extra $$$$ to have the 02 bung mounted in the correct location(brilliant)on SW PART and they still deny any wrong doing and they will NOT pass OBD Emissions testing if required by your State and that's the very reason i went with the PPE Catted DP which are the only ones guaranteed to pass obd emissions testing. Z   http://www.ecopowerparts.com/shop/index.php?main_page=product_info&cPath=1&products_id=150

[FearlessAZ]

I always like to read reviews prior to purchasing a product and here' a review and answer straight from the horses mouth on SW Catted DP. Are your downpipes for my 2010 SHO legal in Arizona?
Asked by: Bill - 6/16/2016
Customer AnswerThese downpipes will not pass emissions testing in Arizona, even the high-flow catted variants. The custom tuning that's required with these downpipes usually involves disabling the O2 sensors to avoid a CEL, and Arizona tests for O2 readiness, as well as for emissions-related CELs.
Was this answer helpful?   YES  NO 2 of 2 Customer(s) found this Answer helpful.
Answer provided by:  Jason@Stage3 (6/16/2016) http://www.stage3motorsports.com/TA10ECODP-2010-2013-Taurus-SHO-3-5L-EcoBoost-Stainless-Works-Downpipes.html   BTW have my own personal opinion on these so called catted DP but rather not go there. Z

Is this just the SW catted? I live in AZ and was planning on getting PPE catted in March. I was under the impression that these wouldn't throw CEL?

[StealBlueSho]

SW Catted Pipes... Doing a lot of good...

[StealBlueSho]

I always like to read reviews prior to purchasing a product and here' a review and answer straight from the horses mouth on SW Catted DP. Are your downpipes for my 2010 SHO legal in Arizona?
Asked by: Bill - 6/16/2016
Customer AnswerThese downpipes will not pass emissions testing in Arizona, even the high-flow catted variants. The custom tuning that's required with these downpipes usually involves disabling the O2 sensors to avoid a CEL, and Arizona tests for O2 readiness, as well as for emissions-related CELs.
Was this answer helpful?   YES  NO 2 of 2 Customer(s) found this Answer helpful.
Answer provided by:  Jason@Stage3 (6/16/2016) http://www.stage3motorsports.com/TA10ECODP-2010-2013-Taurus-SHO-3-5L-EcoBoost-Stainless-Works-Downpipes.html   BTW have my own personal opinion on these so called catted DP but rather not go there. Z

Is this just the SW catted? I live in AZ and was planning on getting PPE catted in March. I was under the impression that these wouldn't throw CEL?

PPE catted downpipes do not throw a CEL according to everyone who has them.

[ZSHO]

I always like to read reviews prior to purchasing a product and here' a review and answer straight from the horses mouth on SW Catted DP. Are your downpipes for my 2010 SHO legal in Arizona?
Asked by: Bill - 6/16/2016
Customer AnswerThese downpipes will not pass emissions testing in Arizona, even the high-flow catted variants. The custom tuning that's required with these downpipes usually involves disabling the O2 sensors to avoid a CEL, and Arizona tests for O2 readiness, as well as for emissions-related CELs.
Was this answer helpful?   YES  NO 2 of 2 Customer(s) found this Answer helpful.
Answer provided by:  Jason@Stage3 (6/16/2016) http://www.stage3motorsports.com/TA10ECODP-2010-2013-Taurus-SHO-3-5L-EcoBoost-Stainless-Works-Downpipes.html   BTW have my own personal opinion on these so called catted DP but rather not go there. Z

Is this just the SW catted? I live in AZ and was planning on getting PPE catted in March. I was under the impression that these wouldn't throw CEL?

Update above.  Z