when to change cats

[motorin on]

do cats wear out and need replacing,is there a benefit in going to more advanced cats

[Wonky]

They do all eventually wear out or the internal substrate comes loose and either rattles or can even effectively block your exhaust. From memory factory cats are 400cpsi (cells per square inch) whereas aftermarket like the Ballistic cats Sureflo sell are only 100cpsi and therefore flow much better (bigger holes). However, they're definitely illegal (technically) though I've never heard of anyone being done for specifically them. I think to be legal aftermarket cats now on VE have to meet Euro4 specs and be 200cpsi or more, but then of course we get into the whole murky area whereby according to some recent posts everything which can affect emissions and ADRs i.e. exhaust, intake, tune etc has to supposedly be exact factory specs. Where do you draw the line? :confused:

Going with something like Ballistic cats may give you around 5rwkw and a slightly louder, deeper note.

[1BEAST2NV]

I have magnaflows.

[qwigybo]

price v gain are aftermarket cats worth it in peoples opinion ? for a possible 5rwkw increase i can't seem to justify the $600 odd

[Angeldust]

i had a cat blow out on my vx....

horrible noise it made, lost heaps of power and barely limped it home. lol i was worried i blew something
much more than just a cat...

[lukemcg]

price v gain are aftermarket cats worth it in peoples opinion ? for a possible 5rwkw increase i can't seem to justify the $600 odd

Im pretty sure the ballistic cats from Sureflo are around 185 each.

[mechatron]

Im pretty sure the ballistic cats from Sureflo are around 185 each.

There is also generally an additional $150-$200 for piping, flanges, gaskets and fitting

[NIXON]

There is also generally an additional $150-$200 for piping, flanges, gaskets and fitting

My exhaust guy installed them for $88, no need to flange and bolt in.

[RAWKUS]

I picked up a pair of 100 CPI Bokka 4" diameter 2.5" in/outMetal Cats off ebay for $280 the pair..have gone up slightly now:
http://www.ebay.com.au/itm/2-x-2-5-High-Flow-Metal-BOKKA-Catalytic-Converters-/330694620184?pt=AU_Car_Parts_Accessories&hash=item4cfeef7418
Have a shroud that can either be used as a heat shield or bash guard depending on how you rotate when welding/mounting.
Exhaust shop had no probs fitting them, look quite good, standing up well and system sounds great. Cost me about $300 to have fitted with supplied pacemaker extractors and catback on an LS1 Adventra including new flanges/gaskets and mild steel pipe.

[mechatron]

My exhaust guy installed them for $88, no need to flange and bolt in.

Thats quite cheap. I suppose it all depends on whether your old piping & flanges can be reused for the new cats

[whitels1ss]

Thats quite cheap. I suppose it all depends on whether your old piping & flanges can be reused for the new cats
Yes also the size of the piping, the early LS1 had 2 1/4 pipes going to the cats reducing to 2.0 inch inlet and outlet of the cats, the 2.0 restriction on the inlet and outlet was more than of a restriction than the 400 cells inside it with the stock cats and engine pipes.
I can't see the point in even welding 2 1/2 or 3.0 inch inlet/outlet cats into a standard 2 1/4 inch pipe so I reckon it would be a waste of time and money if you did not do the whole job properly and replace the pipes and flanges with the bigger stuff all the way through. ;)
Mine cost me around $600 from memory for brand new hi flow cats and cat pipes which go from the headers to the cat back

[motorin on]

price v gain are aftermarket cats worth it in peoples opinion ? for a possible 5rwkw increase i can't seem to justify the $600 odd
I read somewhere that cats can start to deteriorate after 150,000k's and they are expendables like plugs and leads,for me it isn't about kw gain but having the exhaust working as well as possible
My exhaust note is definitely changing so I am thinking the cats may be on the way out and as there is probably no way of checking I can't see any harm in doing a changeover
I don't want mine failing me at the wrong time-better to be proactive and get in 1st

[NIXON]

Thats quite cheap. I suppose it all depends on whether your old piping & flanges can be reused for the new cats

I was lucky with it, only had to cut old ones out and weld new ones in. For once something was easy on the damn car!:smilesandbanana:

[Wonky]

My exhaust guy installed them for $88, no need to flange and bolt in.

I believe Chev's welder Graham charges $120 to install Ballistics on most cars and that includes flanging them. However, that's something I heard and because I bought my full KPM complete with Ballistics (which KPM kindly welded in for me before they had their own 100cpsi cats) I've never had it done by Graham so please check for yourself if you're interested. However, the costs will obviously go up if there is more mucking around involved.

Also, as Ed (whitels1ss) said, it's pointless spending on after market cats if you retain the squashed, narrow factory cat pipes.

[motorin on]

I believe Chev's welder Graham charges $120 to install Ballistics on most cars and that includes flanging them. However, that's something I heard and because I bought my full KPM complete with Ballistics (which KPM kindly welded in for me before they had their own 100cpsi cats) I've never had it done by Graham so please check for yourself if you're interested. However, the costs will obviously go up if there is more mucking around involved.

Also, as Ed (whitels1ss) said, it's pointless spending on after market cats if you retain the squashed, narrow factory cat pipes.
thank's Wonky
I am in NSW so Chevs is a bit far away, I have 2 exhaust shops close to home and I have used both before so I will stop off on my way home and get some prices

[motorin on]

I called into the exhaust shop on the way home
Drove out with new 400cpi Hi Flow cats as he only had one of the 100's cpi in stock,plus he fitted 2 1/4" pipes in place of the 1 7/8" that were currently fitted after the old "cats".All for $500.The rest of the exhaust is already 2 1/4"
It was an extra $200 for the 100 cpi "cats
I looked inside the old cats and could see where the holes were starting to close up
I can hear a difference in the note,it isn't much of a change but it sounds "crisper" and I can hear it through the floor where I couldn't before
I guess the computer will need to adjust for a different gas flow

[mattnsw]

Drove out with new 400cpi Hi Flow cats



Are 400cpi Cats hi-flow?

[mechatron]

I don't want to sound too harsh, but if it was me, I would have gone for 200cpi cats as a minimum and 2.5" piping on both sides of the cats. Every mod i do now, I try to think ahead so I'm not spending money twice in the same area. 200 CPI cats flow twice as well as the stock 400cpi cats and 2.5" piping would have been better for when an exhaust upgrade (headers & twin 2.5" exhaust) are on the cards. The main thing is that you are happy, however I just look back at all the money I've wasted changing the same components (I.e. exhausts, cats, valve springs, diffs...the list goes on) because I didn't think ahead.

[motorin on]

I don't want to sound too harsh, but if it was me, I would have gone for 200cpi cats as a minimum and 2.5" piping on both sides of the cats. Every mod i do now, I try to think ahead so I'm not spending money twice in the same area. 200 CPI cats flow twice as well as the stock 400cpi cats and 2.5" piping would have been better for when an exhaust upgrade (headers & twin 2.5" exhaust) are on the cards. The main thing is that you are happy, however I just look back at all the money I've wasted changing the same components (I.e. exhausts, cats, valve springs, diffs...the list goes on) because I didn't think ahead.

I have decided not to go with headers or change the exhaust BUT I do understand where you are coming from and appreciate your thoughts.
The car exhaust is fine as is,I can get myself into enough trouble with the performance I have now.
I will probably look at external changes (bonnet) and I am just about due for new tyres so I am watching my $$'s

[motorin on]

Are 400cpi Cats hi-flow?
Apparently the new Euro 4 spec one's are,at least that's what he told me,possibly not a huge difference in hole size.
The old cats didn't look healthy inside

[Wonky]

Are 400cpi Cats hi-flow?

+1. I guess that exhaust shop is the only one who says so, in order to get a sale................

[motorin on]

+1. I guess that exhaust shop is the only one who says so, in order to get a sale................
I have renewed my cats and have enlarged the pipes which is what I set out to do at a price I am happy with
Any extra performance,fuel economy or louder exhaust will be a bonus
Apart from that I am not too worried either way

[shaunv8]

Does anyone know how to tell if a cat is blocked(or heading that way)

[bush_basha]

Does anyone know how to tell if a cat is blocked(or heading that way)

give them a tap, if there on there way to failing the 'should' rattle, i had a rattle in mine, but i could hear it idling, took it to an exhaust shop who said cats, took it down sure enough the middle had dislodged, but wasnt blocked it, pipe and big hammer fix that problem :)

[Wonky]

I have renewed my cats and have enlarged the pipes which is what I set out to do at a price I am happy with
Any extra performance,fuel economy or louder exhaust will be a bonus
Apart from that I am not too worried either way

Yep, understand perfectly. Just I never regarded 400cpsi as high flow and was concerned you may have been stooged a bit.

[motorin on]

I have been to this shop b4 and his work has been o.k.or I wouldn't have gone back,I saw the box's they were in and they were labelled Euro 400,they are smaller than the originals,he assured me the holes are slightly larger and flow better
The car is 2004 and 154,000 k's,so new cats will be an improvement whether they be 400's or 100's
Will engine management need to do any adjusting with the new clean cats and bigger pipes between the cats and the first flange,The exhaust is now 2 1/4 all the way from the cat's to the rear muffler.
I went under my usual railway bridge where I like to make a bit of noise and I know the exhaust sounds different- has a deeper bark,and no it is not my imagination

[iloveholden]

So if you are getting a new exhaust these days and want sound and performance, do we still go for 100CPI cats or 200CPI?

Judging by Wonky's post 200CPI are legal and 100CPI arent?

I just thought 100CPI purely due to better flow?

[Wonky]

I believe from things I've read on here that 200cpsi are legal, but also on VEs at least they also need to meet Euro 4 standards. Obviously things like Ballistic Racing cats are illegal but on the other hand I've never heard of anyone being done specifically for them. Sure, people have been done for noise and emissions but with full exhausts like many of us here run passing those tests involves more than just replacing cats anyway. If I had to be tested I'd just have the whole system replaced with the stock one. Simple but annoying..........

[iloveholden]

Yeah i agree with that. I will go 100cpsi cats for pure sound and performance when i order my new system tomorrow.

[Puppeteere]

Judging by Wonky's post 200CPI are legal and 100CPI arent?


I'm pretty sure even 200CPI are illegal if I can recall my conversation with Greg at Sureflo correctly. In my case, i thought I may as well go 100CPI if 200CPI would also fail emissions laws.

[cali.ls1]

random question..... thought i would post it here rather than start a new thread
do older vt and vx have to meet the same emission standards ie euro 3 (i think??) as say a vy or vz??
i just scored 2 magnaflow 59956.... most places are about 200, but this guy accepted an offer of 75+30 shipping (each) on 2 of these from the states (if anyone is looking for some 200cpsi cats)???

http://www.ebay.com.au/itm/330725651232?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649