Question over 'possibly' stuffed cats.

G'day one and all, hoping to get some info/comments on replacing cats.

LS1/HTV1900 (SS Wags auto) with after market Pacemaker 2.5" stainless system (sureflow cats I believe..)

Have noticed (and had a mate also comment on this without prompting) that I have a 'rattle/noise' coming from the rear of the exhaust (sounds like a stone scraping about - initially I thought the mounting brackets had crap in them) but have since noticed (at low/mid revs') that the power is lacking (if I push the pedal towards WOT then power 'seems' fine). So I have been thinking possibly cats are stuffed (although I could also have a fuel issue given WOT seems fine....). I have also noticed that the tail pipe tips have some strange marks on them that I can not explain:

[IMG]http://i923.photobucket.com/albums/a...y/IMG_0210.jpg[/IMG]

[IMG]http://i923.photobucket.com/albums/a...y/IMG_0204.jpg[/IMG]

Noticed the above when giving my wags a wash the other day (I have just returned from a weeks break down the coast, where the car sat with potentially 'some' salt residue in the tips? - so it could be corrosion?)

Anyway, called the shop yesterday to see if I could get a health check but, place is on skeleton staff for another week, so it was decided that I whip my wags down to an exhaust shop to check the cats (could be collapsed?).

Got her up on a hoist yesterday at Midas and the fella there seems to think that at least one of the cats is stuffed.

Just an F.Y.I, re the fuel, I do have AFR sensors installed and can not see any form of leaning out throughout the rev range (via Aeroforce gauges) - seems a little lean at idle but as soon as any throttle is applied, AFR's 'seem' fine (14's) with the appropriate switch to rich when at WOT (11's) - although, light throttle action does seem to be choked and sluggish.......

Ok, back to the cats question:

I have been recommended Balistics 100 cell racing cats, but fella at Midas seems to think that Magnaflow 200 cell would be better for longevity with very little impact to rwhp.

As always, any comments, suggestions, thoughts would be greatly appreciated. If anyone could also give an indication of cost, I would be most grateful.

Thanks as always,

Carlton

Take cats off, knock insides out & reinstall. No more worries of blocked cats.

Before the 'somebody think of the children, you will goto jail for life' crowd chime in about gutted cats while yes it is illegal (and I'm sure plenty of the other mods on vehicles don't meet ADR requirements either) you would be mighty mighty unlucky to get picked up on it. To be honest you have more bad luck of getting EPA'd in which you would be throwing a standard system on anyway to get it passed.

Anyway another thing is the Aeroforces are you using a wide and sensor with them or looking at commanded AFR? The two differ, just a heads up.

Cheers Zorro, yeah i've got the wide band/sensor fitted, i'd still have to get someone to cut and re weld, so may as well change the cats if they are stuffed.....

With it running as Lean as it has been no surprise they're stuffed :(

One of the good things about NZ. When I had the otr and tune we just cut the cats out and put straight pipe in.

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Originally Posted by IJ.

With it running as Lean as it has been no surprise they're stuffed :(

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Attachment 2908i blew my cats out after i but the 2300 on in about 2 months boost presure went up to 15 psi on one bank i was very luckey it wount rev over 3000 they were x force ones , but i seen and /heard of all the brands go over 5 years

Seen heaps of X force ones do that with and without boost. Call them up they will tell you its because your tuner is doing a "fuel dump"
But as far as cats go id recommend the magnaflow cats over the ballistics get as big a cat as you can without having ground clearance issues

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Originally Posted by zorro

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Ok guys, sorry to sound stupid but what are non lean values as I thought 14,s for low revs and 11 for wot are acceptable.? Have I done damage at these AFR's.

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Originally Posted by FrangaFry

Ok guys, sorry to sound stupid but what are non lean values as I thought 14,s for low revs and 11 for wot are acceptable.? Have I done damage at these AFR's.

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Was much leaner than that under boost when you were at my place..
(alzhiemers has kicked in can't remember exactly)

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Originally Posted by IJ.

Was much leaner than that under boost when you were at my place..
(alzhiemers has kicked in can't remember exactly)

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G'day mate, yerp, she was waaaaaaay leaner then; Shaun at Chev's tweaked with the tables a while back and all was sweet but have noticed the lack of punch on half throttle recently ..... this, with the rattle and the marks on the exhaust tips, I can't help thinking something is as miss. Plan is to check/sort the cats and then get Shaun or Chev to check the tune in a week or so.

P.S. - God damn I love those brakes and the new rack *wink* ................... geeez what a 'transformation' it has been .......

Chances are it hurt the Cats abck then and now one has failed and turned in the pipe like Atomic's pic..

Yep agreed 100% on the Rack I get a good apples to apples comparison each time I switch between the Tonner and Addy! :D

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Originally Posted by zorro

Before the 'somebody think of the children, you will goto jail for life' crowd chime in about gutted cats while yes it is illegal (and I'm sure plenty of the other mods on vehicles don't meet ADR requirements either) you would be mighty mighty unlucky to get picked up on it. To be honest you have more bad luck of getting EPA'd in which you would be throwing a standard system on anyway to get it passed.

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I was under the impression that gutted cats could cost you up to a $10,000 fine :shock: whereas even if you get EPAd the fine (if any) is trivial in comparison. I also believe anyone with a half decent sense of smell can pick if you have gutted cats? :confused:

just put a good length self tapper screw through to secure the rattle! thats what i did to wifeys car... 0$ 0 fines

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Originally Posted by Wonky

I was under the impression that gutted cats could cost you up to a $10,000 fine :shock: whereas even if you get EPAd the fine (if any) is trivial in comparison. I also believe anyone with a half decent sense of smell can pick if you have gutted cats? :confused:

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I've been around long enough and the rumour started at 30k fine and worked its way lower :lol: also I don't know a single person or anyone that can prove someone has been given a fine other than defect notice on their exhaust being 'too loud' for hollowed cats.

The smell I wouldn't worry about as fumes are fumes.

In saying that the last thing a roadside officer will do is ask you to jack the car up and give the cats a tap, you will get a notice for inspection on the exhaust as a whole for noise, no different to heaps of people who have received these in the mail and as mentioned earlier a change of exhaust will sort this out.

Ok, so back on topic fellas *grin* ...... I don't think I will run it with hollow cats, so I will be changing them ASAP, what I would like to gauge now is which brand and type of cats to look around for. I don't want to have to be doing this again in another 12 months, so I am thinking 200 cell MagnaFlow cats are the go; My basic understanding is that 100 cell are racing based for better flow etc but will not tolerate too much and have a shorter life span; The 200 cell will restrict the exhaust flow a little more (but I am led to believe not by too much - a couple of HP); I am also led to believe that the MagnaFlow are a metal core and built quite tough and will have a considerably longer life span (especially if I continue to experience some fuel issues in the future).

What are folks thoughts, 100 or 200 and which brand - preferences?

Thanks for all the comments to date.

Cheers

I had ebay bokka cats 2.5in 100 cell for about 3.5 yrs. They had some big knocks on speed bumps etc... shit welds one actually cracked in half and the other was rattling. Upgraded the headers from tri-ys to 4 into 1s and the guy I bought them off threw in some kenobi 3in 200 cell. They look about the same quality as the bokka ones but will do the job for a while. As mentioned they all seem to fail, if I had to buy again it would be the magnaflow 200 cell, (flat design) ones but will more than likely put a crow bar through them if they start rattling.

Like many people I've had Ballistics in for almost 5 years now (70,000km approx) with no problems at all, even after hitting the odd speed bump or three.

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Originally Posted by zorro

Take cats off, knock insides out & reinstall. No more worries of blocked cats.

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I agree. Bash em out and refit. Happy days !!