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      03-17-2010, 11:25 AM   #1
CSanto
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Teach me the complications of a middle Exhaust.

I'm looking into doing some power upgrades (middle exhaust, pully, tune). I've come to the conclusion that if I don't intend to do the middle exhaust the other modifications are pointless.

This is because deleting the primary cats results in the most power gain as everyone here knows.

I'd like all the knowledge of the board to teach me the implications of deleting your primary cats.
For example, how bad really is the smell? Will it bother me? can you smell it in the car? while idling? only under WOT?

How do you pass inspection? Pay someone off to pass it? Swap parts for the inspection? How do you guys accomplish this?

Finally, what are the implications with the CEL. I know I need a tune, but what exactly does this do? Delete the emissions reader? I wont have any problems with the CEL correct? I would honestly hate to have to look at that icon on my dash.

I'm looking at the Dinan middle-exhaust right now.

Thank you for all your help!

Chris
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      03-17-2010, 11:48 AM   #2
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      03-17-2010, 12:04 PM   #3
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Are you deleting the primary cats and secondary? How about exhaust?

Im running 200 cel cats and you can definately smell it. Cruising around you shouldnt smell anything. The only time your really going to smell anything is when your idling.
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      03-17-2010, 12:17 PM   #4
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Yes, the Dinan middle exhaust deletes the primary and secondary cats.
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      03-17-2010, 12:43 PM   #5
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good thread topic. I too am looking to do the exact same 3 mods..but am a little cautious to pull the trigger. I cannot decide on parts and smell/sound levels are definitely a concern of mine.

Dinan mid pipes require the software upgrade to not throw codes...correct?
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      03-17-2010, 12:53 PM   #6
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You can pretty much only smell it at a stoplight or in the garage when you start the car up. It's really not that bad unless you're really sensitive.

The tune will simply turn off the CEL. If you get the full Dinan system with their software you will not have any CEL problems.
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      03-17-2010, 12:55 PM   #7
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imho the few horses you get from deleteing the primary cat is not enough for the constant changes back to stock for emissions, smells, etc. it not like you already use all your 414 horses anyway .

if i were doing exhaust i would leave the primary on and get a slip on from there that would just delete the 2nd cat and resonator followed by connecting and muffler. more then enough for me and i don't have to worry about smell or passing emissions, this alone is priceless.

i would either get the aa stubbies with aa xpipe and a connecting and a muffler or the challenge slip on followed by connecting and muffler.
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      03-17-2010, 01:02 PM   #8
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Deleting primary and second cats on stock exhaust you will have shitty sounding car with CEL and some more hp before it wents to engine limp mode. So you will need ECU remap and back exhaust too(so it's extra money). Is't it better to delete secondary cats & resonators and put some nice sounding exhaust ?
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      03-17-2010, 01:26 PM   #9
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I have an ES currently
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      03-17-2010, 01:35 PM   #10
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Lets say you keep the stock muffler to keeps sounds close to stock. The question now is which of the two options below has the least "toxic" smell that you can tolerate.

1. Deleting primary cats ( and istalling turner motorsport straight pipe) and keeping OEM secondary cats/resonators.

2. High flow cats (200 cells) and also deleting secondary OEM cats/resonatros (X-pipe)

I think option 1 is more tolerable, but not sure. Hopefully others can answer this question.
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      03-17-2010, 02:29 PM   #11
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FWIW, I weighed all these options as well... and decided to pull the trigger.

I am having the Dinan mid and rear exhausts installed next Wednesday.

Updates will follow as soon as I drive outta the shop and test it out...
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      03-17-2010, 03:24 PM   #12
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Quote:
Originally Posted by HREM3 View Post
I'm looking into doing some power upgrades (middle exhaust, pulley, tune). I've come to the conclusion that if I don't intend to do the middle exhaust the other modifications are pointless.
This is basically true if you want to achieve some substantial gains by upgrading your exhaust system, although just the removal of the SECONDARY CATS and a free-flowing muffler section can also extract some modest HP & TRQ gains as well.

Quote:
Originally Posted by HREM3 View Post
This is because deleting the primary cats results in the most power gain as everyone here knows.
Correct. The stock OEM 400-cell ceramic brick catalytic converters are the #1 obstacle to improving your exhaust system's performance. The removal of these restrictive exhaust system components will allow a greater VOLUME of exhaust gases to pass through the system with increased velocity. This will improve your HP & TRQ throughout the entire rev band.

Quote:
Originally Posted by HREM3 View Post
I'd like all the knowledge of the board to teach me the implications of deleting your primary cats.
The only two negative implications to deleting your PRIMARY cats are:

a) Dealing with an annoying, and re-occurring CEL light for catalyst deficiency if you completely remove the primary cats. This can be addressed with a software tune to disable the rear O2 sensor cat deficiency warning. (a new hard-wired CEL delete module is showing promising results so far in testing)

b) You will automatically fail an emissions readiness test for states that require strict emissions system compliance. This applies to any state that uses OBD-II ECU device that plugs into the car to check for emissions system readiness, and any existing ECU or Emissions related fault codes that are stored in the ECU's memory.

Quote:
Originally Posted by HREM3 View Post
For example, how bad really is the smell? Will it bother me? can you smell it in the car? while idling? only under WOT?
I can only speak for myself here, but I can't stand the smell of a catless car. I made the huge mistake of buying catless AA "test pipes" for my Dinan supercharged E36 M3 a long time ago. The smell of unburned gasoline made me gag! I'm sure others will disagree with my take. I don't want my $60,000 car to smell like a damn gas station.

Quote:
Originally Posted by HREM3 View Post
How do you pass inspection? Pay someone off to pass it? Swap parts for the inspection? How do you guys accomplish this?
Think about it. I'm sure you can figure out what is needed here.

Quote:
Originally Posted by HREM3 View Post
Finally, what are the implications with the CEL. I know I need a tune, but what exactly does this do? Delete the emissions reader? I wont have any problems with the CEL correct? I would honestly hate to have to look at that icon on my dash.
It kills the CEL light that pops up on the dash. (so that it doesn't constantly annoy you) The exhaust fault code that triggers this CEL, will still be there if you scan the ECU with an 16-pin OBD-II compliant code reader.

Quote:
Originally Posted by HREM3 View Post
I'm looking at the Dinan middle-exhaust right now.
If you are going to go with a catless middle exhaust section, this is the best x-pipe on the market (by far) IMO.

I wrote a long post on the Dinan middle exhaust about a week ago. The build construction, fitment, and the extensive R&D testing that went into that middle exhaust piece is very impressive.

Quote:
Originally Posted by HREM3 View Post
Thank you for all your help!

Chris
You're welcome. lol...
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      03-17-2010, 04:20 PM   #13
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Lemans_Blue - great post. Question: If you go with a HFC (200 cel) does that effectively get rid of the "smell" you referred to with a cat-less set up?

I read on here from someone that they still had a smell w/200 cel HFC's, which was new to me...I thought that would pretty much remove any odors.
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      03-17-2010, 04:24 PM   #14
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I'm thinking that the loudness will definitely attract the attention of the authorities and might give them the reason to pull you over suspecting that you're running without any cats.
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      03-17-2010, 04:33 PM   #15
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Quote:
Originally Posted by Fen335i View Post
Lemans_Blue - great post. Question: If you go with a HFC (200 cel) does that effectively get rid of the "smell" you referred to with a cat-less set up?

I read on here from someone that they still had a smell w/200 cel HFC's, which was new to me...I thought that would pretty much remove any odors.
200 cel hfc's dont do shit and whoever says that they do id love for them to come down and take a whiff of my car
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      03-17-2010, 04:35 PM   #16
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Quote:
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200 cel hfc's dont do shit and whoever says that they do id love for them to come down and take a whiff of my car
What are you running for exhaust setup? Did you double check for leaks?
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      03-17-2010, 04:41 PM   #17
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Quote:
Originally Posted by armorrig View Post
I'm thinking that the loudness will definitely attract the attention of the authorities and might give them the reason to pull you over suspecting that you're running without any cats.
Here's the deal guys...

Removal of the primary cats is not going to substantially increase the loudness of the M3's exhaust system...IF the secondary cats and resonators are still in place. That's the reason I didn't list it as an implication to the removal of the PRIMARY CATS, which is the specific question that was asked by the OP.

Think about the design of the Akrapovic Evolution exhaust system for a minute...and it'll make sence to you.

The removal of both the primary and secondary cats WILL lead to a substantial increase in the volume of your exhaust system. Now the removal of both sets of cats, plus the 2 factory resonators will yield the highest decibel levels, since there would be nothing to silence the exhaust note whatsoever. (coming out of the headers)

Adding an aftermarket muffler that features a straight-through can design (no internal baffling or diffuser pipes) and the sound would be deafening.
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      03-17-2010, 04:52 PM   #18
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awesome information thanks guys
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      03-17-2010, 04:52 PM   #19
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Quote:
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What are you running for exhaust setup? Did you double check for leaks?
I have no leaks. Im running Encore pipes.
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      03-17-2010, 05:31 PM   #20
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Quote:
Originally Posted by Fen335i View Post
Lemans_Blue - great post. Question: If you go with a HFC (200 cel) does that effectively get rid of the "smell" you referred to with a cat-less set up?

I read on here from someone that they still had a smell w/200 cel HFC's, which was new to me...I thought that would pretty much remove any odors.
Well...NO, it doesn't completely "get rid of of the smell" entirely, but it does REDUCE the toxic smell of unburned fuel and hydrocarbons that are the end result of an inefficient burn process of your typical internal combustion engine. (only about 50% of the fuel energy potential is actually used to make power) The rest is dissipated as heat and unburned fuel through the exhaust system.


200-cell metal matrix race cats will effectively burn off a larger percentage of the hydrocarbons that are present in the exhaust gas stream. (once they reach their ideal operating temperature) 200-cell cats make it much more tolerable for some people. (including myself)


It doesn't remove all the hydrocarbons from the exhaust gas stream, however, this option is a great improvement over NO CATS of course. (or even 100-cell cats)

No high flow catalytic converter option should ever be viewed as a viable replacement for the higher 400-cell count OEM catalytic converters. (that are actually EPA certified) The OEM cats will of course remove the highest percentage of hydrocarbon emissions for your exhaust system, due to the density and nature of the catalytic substrate material used (ceramic honeycomb impregnated /w/ silica), and the wash-coat. (small amounts of platinum, palladium, & rhodium)

Not that anyone here cares about that stuff.
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      03-17-2010, 05:33 PM   #21
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Quote:
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200 cel hfc's dont do shit and whoever says that they do id love for them to come down and take a whiff of my car
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      03-17-2010, 05:36 PM   #22
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Quote:
Originally Posted by Lemans_Blue_M View Post
Well...NO, it doesn't completely "get rid of of the smell" entirely, but it does REDUCE the toxic smell of unburned fuel and hydrocarbons that are the end result of an inefficient burn process of your typical internal combustion engine. (only about 50% of the fuel energy potential is actually used to make power) The rest is dissipated as heat and unburned fuel through the exhaust system.


200-cell metal matrix race cats will effectively burn off a larger percentage of the hydrocarbons that are present in the exhaust gas stream. (once they reach their ideal operating temperature) 200-cell cats make it much more tolerable for some people. (including myself)


It doesn't remove all the hydrocarbons from the exhaust gas stream, however, this option is a great improvement over NO CATS of course. (or even 100-cell cats)

No high flow catalytic converter option should ever be viewed as a viable replacement for the higher 400-cell count OEM catalytic converters. (that are actually EPA certified) The OEM cats will of course remove the highest percentage of hydrocarbon emissions for your exhaust system, due to the density and nature of the catalytic substrate material used (ceramic honeycomb impregnated /w/ silica), and the wash-coat. (small amounts of platinum, palladium, & rhodium)

Not that anyone here cares about that stuff.
Thanks Lemans_Blue

I know it varies state by state for emissions testing, but if you go w/a 200-cell cat, what are the chances of passing emmissions (assuming you have an ECU tune as well - however not sure if that even matters, given what I just read about removing the light from your dash does not remove it from the ECU's memory!)
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