Cats - how restrictive are they?
08-21-2007, 09:43 AM
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Cats - how restrictive are they?
Has anyone looked inside of the primary cats and the secondary cats. Pictures would be great. Thinking of removing one or the other, as I don't think my car needs both. Is one more restrictive than the other?
08-21-2007, 09:46 AM
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The primary cats are more restrictive, removing them yields about 7-10 rwhp.
08-21-2007, 10:00 AM
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08-21-2007, 10:02 AM
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These are the ones i'm using and they have been highly recommended Frank!
Everyone trie to copy them and put out fakes as well.
http://www.metalcat.com.au/
Last edited by ProjectC55; 08-21-2007 at 10:04 AM.
08-21-2007, 10:07 AM
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08-21-2007, 11:10 AM
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SL65 AMG
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These are the ones i'm using and they have been highly recommended Frank!
Everyone trie to copy them and put out fakes as well.
http://www.metalcat.com.au/
These are the ones i'm using and they have been highly recommended Frank!
Everyone trie to copy them and put out fakes as well.
http://www.metalcat.com.au/
08-21-2007, 11:23 AM
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Frank,
I looked at both and they are pretty restrictive...Definately remove PRIMARY CATS !!! The car will pass emissions with just secondary cats...
Primary Cats give the most POWER...As Cory Kleemann said 15HP at the wheels on Dyno and you car feel it...
Its not hard to remove them and make long tubes instead, place you rear O2 sensors which are behind Primary cats, behind the Secodary cats and you wont have any SES light and wont have to adjsut your ECU ...just extend wire by wire...its not very hard to do...
I went throught this...I had regular bolt headers before...then remove Primary Cats and later Secondary...
Secodary Cats dont make to much power, and again Vadim and Cory told ME they aree they are least worth 5-10HP at the crank...
I WOULD NOT reccomend removing just Secondaries and keeping Primaries...As I beleive, the system becomes too Freeflowing after Primary Cats (if primaries a not removed) and you could loose torgues !!!
IMHO here not enough FLOW rate since Primaries are restricting the flow and not enough flow from Primary Cats for gases to leave fast enough with Secodaries removed, cuase again primaries reduce that speed...and that us why Vic55 lossed torgues before when he removed Secodaries and installed E.Race mufflers...
So basiaclly gases come fast to Primaries then slow down and then if we remove Secodary cats the speed increeases but not from the Headers but from Primaries and that is not the same...not enough pressure from primaries, since speed and decreased and the rest of the exhaust to to freem so gases stqay longer inthe system or something like this...
The system becomes to freeflowing for gases to leave fast enough or may be the gases get colder and that means the dont leave the system fast enough, cause the slowed down already...anyways that my theory...every one knows that LONG TUBES Header make the most POWER !!!
Its hard to explain...just remove Primary Cats and you will be happy my friend
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08-21-2007, 11:29 AM
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08-21-2007, 11:32 AM
#9
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ъ
Frank,
I looked at both and they are pretty restrictive...Definately remove PRIMARY CATS !!! The car will pass emissions with just secondary cats...
Primary Cats give the most POWER...As Cory Kleemann said 15HP at the wheels on Dyno and you car feel it...
Its not hard to remove them and make long tubes instead, place you rear O2 sensors which are behind Primary cats, behind the Secodary cats and you wont have any SES light and wont have to adjsut your ECU ...just extend wire by wire...its not very hard to do...
I went throught this...I had regular bolt headers before...then remove Primary Cats and later Secondary...
Secodary Cats dont make to much power, and again Vadim and Cory told ME they aree they are least worth 5-10HP at the crank...
I WOULD NOT reccomend removing just Secondaries and keeping Primaries...As I beleive, the system becomes too Freeflowing after Primary Cats (if primaries a not removed) and you could loose torgues !!!
IMHO here not enough FLOW rate since Primaries are restricting the flow and not enough flow from Primary Cats for gases to leave fast enough with Secodaries removed, cuase again primaries reduce that speed...and that us why Vic55 lossed torgues before when he removed Secodaries and installed E.Race mufflers...
So basiaclly gases come fast to Primaries then slow down and then if we remove Secodary cats the speed increeases but not from the Headers but from Primaries and that is not the same...not enough pressure from primaries, since speed and decreased and the rest of the exhaust to to freem so gases stqay longer inthe system or something like this...
The system becomes to freeflowing for gases to leave fast enough or may be the gases get colder and that means the dont leave the system fast enough, cause the slowed down already...anyways that my theory...every one knows that LONG TUBES Header make the most POWER !!!
Its hard to explain...just remove Primary Cats and you will be happy my friend
Frank,
I looked at both and they are pretty restrictive...Definately remove PRIMARY CATS !!! The car will pass emissions with just secondary cats...
Primary Cats give the most POWER...As Cory Kleemann said 15HP at the wheels on Dyno and you car feel it...
Its not hard to remove them and make long tubes instead, place you rear O2 sensors which are behind Primary cats, behind the Secodary cats and you wont have any SES light and wont have to adjsut your ECU ...just extend wire by wire...its not very hard to do...
I went throught this...I had regular bolt headers before...then remove Primary Cats and later Secondary...
Secodary Cats dont make to much power, and again Vadim and Cory told ME they aree they are least worth 5-10HP at the crank...
I WOULD NOT reccomend removing just Secondaries and keeping Primaries...As I beleive, the system becomes too Freeflowing after Primary Cats (if primaries a not removed) and you could loose torgues !!!
IMHO here not enough FLOW rate since Primaries are restricting the flow and not enough flow from Primary Cats for gases to leave fast enough with Secodaries removed, cuase again primaries reduce that speed...and that us why Vic55 lossed torgues before when he removed Secodaries and installed E.Race mufflers...
So basiaclly gases come fast to Primaries then slow down and then if we remove Secodary cats the speed increeases but not from the Headers but from Primaries and that is not the same...not enough pressure from primaries, since speed and decreased and the rest of the exhaust to to freem so gases stqay longer inthe system or something like this...
The system becomes to freeflowing for gases to leave fast enough or may be the gases get colder and that means the dont leave the system fast enough, cause the slowed down already...anyways that my theory...every one knows that LONG TUBES Header make the most POWER !!!
Its hard to explain...just remove Primary Cats and you will be happy my friend
I agree with Russ 100%. If it were my car I'd get rid of the primaries and replace the secondaries with the Metal Cats. And like Chiromikey has done I highly advise adding a X-pipe in the system I believe just after the Cats. He can give you more of a low down on that with pics I might add.
PS I modded my O2's the exac way Russ did as well. No SES lights no nothing. Never had to modify my ECU as well.
Last edited by ProjectC55; 08-21-2007 at 11:57 AM.
08-21-2007, 11:48 AM
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is it safe to assume you already have shorty headers?
08-21-2007, 12:00 PM
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iirc, the primary and secondary are both 400 cel cats of identical design. the reason to remove primary over secondary has to do with location rather than the cat itself and removing primaries has been said to yield more hp gains than removing the secondary.
is it safe to assume you already have shorty headers?
is it safe to assume you already have shorty headers?
08-21-2007, 12:01 PM
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iirc, the primary and secondary are both 400 cel cats of identical design. the reason to remove primary over secondary has to do with location rather than the cat itself and removing primaries has been said to yield more hp gains than removing the secondary.
is it safe to assume you already have shorty headers?
is it safe to assume you already have shorty headers?
08-21-2007, 12:11 PM
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08-21-2007, 12:14 PM
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But it does not mean that yours will be as loud. But it will be louder than it is now. Much Quieter than Will's,Joons and Jody's cars if you don't use the Eisenman exh
. I still have my stck muffler on and I think Chiro did as well.The decrease in weight alone will have you feeling a difference I might add.
08-21-2007, 01:40 PM
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08-21-2007, 01:43 PM
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08-21-2007, 01:47 PM
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LOL! I told you it's a thing of beauty. Who do you think gave me the idea of how to build my exh!
Junior at RCT can build you the same system unless Chiro has one made already. I'd perhaps get Chiro to have the headers built if you are interested in those and let Junior build the rest of the exh for you!
Junior at RCT can build you the same system unless Chiro has one made already. I'd perhaps get Chiro to have the headers built if you are interested in those and let Junior build the rest of the exh for you!
08-21-2007, 01:49 PM
#21
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He has no primaries! The reso's will quiet the car some since you don't want the car to sound crazy.The long tube headers eliminated the primary cats.. I'd ask him what is the diameter of the Cats and the rest of the exh piping!
Hopefully Chiro can post a dyno as well and give us some idea of how the car feels.
Hopefully Chiro can post a dyno as well and give us some idea of how the car feels.
Last edited by ProjectC55; 08-21-2007 at 01:51 PM.
08-21-2007, 02:21 PM
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08-21-2007, 02:30 PM
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The stock exhaust system after the primary cats is actually quite good and will support a lot of horsepower. Modding the factory exhaust will yield minimal results at best from my experience.
08-21-2007, 02:32 PM
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E55
Even the cats? Thinking about removing the primary cats and replacing the secondary cats with racing cats..
