I've been thinking about a catless downpipe for a few months now. The warranty is long gone, I'm not getting younger, maybe it's time to take the noisy little hatch up a notch on the crazy scale. But as a 3 season daily, would I end up regretting it? I definitely don't look forward to a CEL all the time.
The product:
A good comparison video:
Shorter video of before/after:
...damn that sounds good though.
Maybe a higher flowing cat would be a good compromise? Mo noise without mo check engine light?
In reply to wae :
I'm considering it. RRM High Flow cat downpipe
Is there not a tune available to:
1. Eliminate the CEL
2. Take advantage of the dramatically increased flow to make a chunk more HP?
I'm currently debating this same thing on my 135i. I want to do a full turbo-back exhaust, but I also don't want to make it noise and annoying for the daily commute.
z31maniac said:Is there not a tune available to:
1. Eliminate the CEL
2. Take advantage of the dramatically increased flow to make a chunk more HP?
I'm currently debating this same thing on my 135i. I want to do a full turbo-back exhaust, but I also don't want to make it noise and annoying for the daily commute.
Careful throwing around #2 as a reason to ditch a cat.. Modern cats are extremely efficient and rarely does removing one result in decreased backpressure or noticeably increased power levels. I think there was an article that GRM did that showed that on a dyno as well.
z31maniac said:Is there not a tune available to:
1. Eliminate the CEL
2. Take advantage of the dramatically increased flow to make a chunk more HP?
I'm currently debating this same thing on my 135i. I want to do a full turbo-back exhaust, but I also don't want to make it noise and annoying for the daily commute.
If there was one, it would be very illegal to sell it.
As a matter of fact, the downpipe that is being sold is illegal to sell, too. Especially if there's no "Off Road Use Only" caveat from the seller.
z31maniac said:Is there not a tune available to:
1. Eliminate the CEL
There are some ways around this, based on the interwebs people have varying degrees of sucess.
The first is a o2 'simulator' boxes that will send a 'good' signal back to the ECM to make it think the o2 is working as it should. I've never used one so i dont know how well they work but they seem reasonably poplular.
The second is using 1 or 2 spark plug non-foulers. The idea is that this moves the head of the o2 sensor out of the direct exhaust stream which somehow makes it think a cat is still in place. I used 2 of these non-foulers when i deleted the cat in my Audi A4 1.8t and never got a CEL for 2+ years.
Not saying that either trick will work 100% but in some cases it does the job
Don't delete your cat. There are no performance gains, only headaches to be had from CELs and fumes. Abarths already sound sexy from the factory. Maybe go for a different/deleted muffler.
After watching those clips I actually prefer the stock sound.
Narrator: And it was at that exact moment that STM317 realized he was old.
Without commenting on the moral or legal discussion, to suggest that there are no gains from removing a cat in a down pipe, or a pre-cat is incorrect. There have been significant differences on every turbo car I've done it to and in the latest non-turbo application it was dyno verified on a Chevy Colorado at 17hp.
Suprf1y said:Without commenting on the moral or legal discussion, to suggest that there are no gains from removing a cat in a down pipe, or a pre-cat is incorrect. There have been significant differences on every turbo car I've done it to and in the latest non-turbo application it was dyno verified on a Chevy Colorado at 17hp.
This. Even modern Naturally aspirated cars pick up noticeable HP with cat removal and a tune.
The Twins for example pickup around 15-20 whp with a cat delete and tune, only around 7-10hp with a tune, assuming pump gas. Not E85.
alfadriver said:z31maniac said:Is there not a tune available to:
1. Eliminate the CEL
2. Take advantage of the dramatically increased flow to make a chunk more HP?
I'm currently debating this same thing on my 135i. I want to do a full turbo-back exhaust, but I also don't want to make it noise and annoying for the daily commute.
If there was one, it would be very illegal to sell it.
As a matter of fact, the downpipe that is being sold is illegal to sell, too. Especially if there's no "Off Road Use Only" caveat from the seller.
This isn't new information. Anything you do to a vehicle that modifies the emissions system (cat removal, tuning the ECU, etc) has been illegal in all 50 states for a few decades now.
High flow CATs cost more than bypass pipes but what is your social conscience worth to you?
On some of the cars I deal with, a high flow CAT doesn't reduce power over a simple pipe when dynoed.
z31maniac said:alfadriver said:z31maniac said:Is there not a tune available to:
1. Eliminate the CEL
2. Take advantage of the dramatically increased flow to make a chunk more HP?
I'm currently debating this same thing on my 135i. I want to do a full turbo-back exhaust, but I also don't want to make it noise and annoying for the daily commute.
If there was one, it would be very illegal to sell it.
As a matter of fact, the downpipe that is being sold is illegal to sell, too. Especially if there's no "Off Road Use Only" caveat from the seller.
This isn't new information. Anything you do to a vehicle that modifies the emissions system (cat removal, tuning the ECU, etc) has been illegal in all 50 states for a few decades now.
So how would you suggest finding some one to sell it to you? Is there some kind of black market for new calibrations? Or do you think someone will just give it to you with their hard work?
BTW, if you ask the EPA, YOU as the car owner can't be prosecuted by them for making the modification. The state might, but the feds wont. What they can do is penalize whoever sells it to you. I called and asked about it once.
If you want more sound, switch to a higher-flowing muffler. If you want less backpressure, first you have to figure out what the most restrictive element is, it's rarely the cat on modern cars. Deleting the cat only makes sense if the cat is the most restrictive element AND you don't care about the downsides of removing the cat (health + environmental + legal + ECU error codes).
Abarth 500s don't have a muffler. Just a turbo and a cat.
In the first video when I heard the catless pipe I thought it sounded terrible. Blatty and hollow with the big rig diesel turbine noise.
Second video sounded nice in the upper revs. There is no way I could deal with the extra volume though.
Jumper K Balls said:Abarth 500s don't have a muffler. Just a turbo and a cat.
Yup. I believe resonator tips? I've heard a few aftermarket exhausts at the Tail of the Dragon events, liked none as well as the OEM. Just looking for "more".
alfadriver said:z31maniac said:alfadriver said:z31maniac said:Is there not a tune available to:
1. Eliminate the CEL
2. Take advantage of the dramatically increased flow to make a chunk more HP?
I'm currently debating this same thing on my 135i. I want to do a full turbo-back exhaust, but I also don't want to make it noise and annoying for the daily commute.
If there was one, it would be very illegal to sell it.
As a matter of fact, the downpipe that is being sold is illegal to sell, too. Especially if there's no "Off Road Use Only" caveat from the seller.
This isn't new information. Anything you do to a vehicle that modifies the emissions system (cat removal, tuning the ECU, etc) has been illegal in all 50 states for a few decades now.
So how would you suggest finding some one to sell it to you? Is there some kind of black market for new calibrations? Or do you think someone will just give it to you with their hard work?
BTW, if you ask the EPA, YOU as the car owner can't be prosecuted by them for making the modification. The state might, but the feds wont. What they can do is penalize whoever sells it to you. I called and asked about it once.
The same was they have for a few decades now "FOR OFFROAD USE ONLY" "USE AT YOUR OWN RISK" etc.
I'm not really sure what you are trying to get at.
z31maniac said:The same was they have for a few decades now "FOR OFFROAD USE ONLY" "USE AT YOUR OWN RISK" etc.
I'm not really sure what you are trying to get at.
To be fair, stuff like this is the reason why the EPA would crack down on aftermarket companies. That "Jegs" thread recently that got people worked up was centralized around this issue. If people buy something labeled "off road use only", and use it on road, they're only hurting the future of the car hobby as a whole. As car lovers, we need to realize that we're cutting off our nose to spite our face when it comes to stuff like this.
z31maniac said:Suprf1y said:Without commenting on the moral or legal discussion, to suggest that there are no gains from removing a cat in a down pipe, or a pre-cat is incorrect. There have been significant differences on every turbo car I've done it to and in the latest non-turbo application it was dyno verified on a Chevy Colorado at 17hp.
This. Even modern Naturally aspirated cars pick up noticeable HP with cat removal and a tune.
The Twins for example pickup around 15-20 whp with a cat delete and tune, only around 7-10hp with a tune, assuming pump gas. Not E85.
Were these controlled comparisons using otherwise identical systems, with the only difference being a high follow cat vs straight pipe? Same larger than stock piping, same muffler(s), same equivalent tune from same tuner?... Or is it vs smaller diameter stock, or some other such uncontrolled anecdote? Sources?
Jerry said:I've heard a few aftermarket exhausts at the Tail of the Dragon events, liked none as well as the OEM. Just looking for "more".
Are there any catted exhausts available, maybe even with similarly resonated tips, that are simply larger diameter than stock?
Driven5 said:z31maniac said:Suprf1y said:Without commenting on the moral or legal discussion, to suggest that there are no gains from removing a cat in a down pipe, or a pre-cat is incorrect. There have been significant differences on every turbo car I've done it to and in the latest non-turbo application it was dyno verified on a Chevy Colorado at 17hp.
This. Even modern Naturally aspirated cars pick up noticeable HP with cat removal and a tune.
The Twins for example pickup around 15-20 whp with a cat delete and tune, only around 7-10hp with a tune, assuming pump gas. Not E85.
Were these controlled comparisons using otherwise identical systems, with the only difference being a high follow cat vs straight pipe? Same larger than stock piping, same muffler(s), same equivalent tune from same tuner?... Or is it vs smaller diameter stock, or some other such uncontrolled anecdote? Sources?
Yes, there are comparisons using the stock header and just knocking out the cat.
Sources? I have better things to do then go back and search the 86 forums for old threads to show you. You're more than welcome to do your own research, or perhaps you show me your sources that say it doesn't matter?
Hell, ask some tuners if they have different tunes for catted and catless headers or catted vs catless downpipes on turbo cars, HINT: They do. Same on my 135i and many other cars, because their is a difference.
Same here.
The Colorado comparison was done back to back on the same dyno with a 3.7L inline 5 with no tune.
On my own turbo cars they weren't dyno'd or tuned, but timed, and being turbo there are other things at play.
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