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So many variables, I've read X-Force cheat and don't attach a catback to the end of the cat when they test, to get those high values. Also Metalcat and Catco cats actually pass EPA emission tests, while X-Force and the other ripoffs don't.

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Catco's ceramic cat is 428cfm, but their metal cat is 706CFM. I went the catco metal cat (706CFM).

Claimed flow rates are all bullshit unless they tell you what pressure drop (through the part under test) they were done at.

very very few manufacturers state the pressure figure.

Well, the real test would be chucking the exact same car on the exact same dyno with the stock cat and then with each of these aftermarket ones, all other things unchanged.

I wonder what the real-world performance difference is between 428CFM, 570CFM and 706CFM cats (claimed or real, at whatever pressure drop) in a ~200 rwkw car?

These are for the ceramic cats, not metallic. Note that 'stainless' refers to casing not catalyser type.

I went with the XForce in the end due to (claimed) higher flow rate. So far so good.

Catco's ceramic cat is 428cfm, but their metal cat is 706CFM. I went the catco metal cat (706CFM).

Claimed flow rates are all bullshit unless they tell you what pressure drop (through the part under test) they were done at.

very very few manufacturers state the pressure figure.

Totally agree.

Hence i usually would suggest a basic rule like this:

3" exhaust - at LEAST a 3.5" CAT

3.5" exhaust - at LEAST a 4" CAT, preferrably 4.5"

People using 3" CAT's with 3" exhausts, it doesn't surprise me you notice performance degradation - Just have a look inside the CAT and you'll soon workout why :(

You need something a bit bigger.

I notice when I have my CATCO 4" CAT in the car (3.5" exhaust). It's not a major performance hit (270rwkw), but i can feel it none the less.

Ideally i need a 4.5" CAT :P

ok so if i got a 3 inch front pipe into a 3.5 inch exhaust, is a 4 inch cat gunna fit there and can i get one that isnt 400$..

If so where ya get em from...? all im finding is 3inch the occasional 3.5 but 400$ is outta my budget atm..some cheapies on ebays under 200 but guessing there poo...Car is almost done and ready for tune,(hoping for 250ish) but i want the exhaust right first,please help... :)

has anyone actually tried one of those metalcat ones? like hows the length compare to a nissan cat - if its too long its gonna be no good if its too short u'll have to dodgily extend it. might give Repco a buzz tomorrow just to price up a couple

Well do you think a cheap one will be any good if all of them are around $400? :)

That didnt help man,

So after all my good work and bargain hunting i have no choice but to waste 400$ on something that is essentially useless...

That didnt help man,

So after all my good work and bargain hunting i have no choice but to waste 400$ on something that is essentially useless...

Pretty sure he was saying you get what you pay for,

If you've read the posts there's heaps of guys that have bought the cheap ceramic ones and they have melted.

I'm sure the one you bought for $400 is metal, and it would more than likely flow twice as good as the ceramic cat.

So..... you get what you pay for.

has anyone actually tried one of those metalcat ones? like hows the length compare to a nissan cat - if its too long its gonna be no good if its too short u'll have to dodgily extend it. might give Repco a buzz tomorrow just to price up a couple

Actually the cat's come overlength, all the exhaust shop has to do is cut down each end and weld the flanges on to suit... Its a very easy job.

That didnt help man,

So after all my good work and bargain hunting i have no choice but to waste 400$ on something that is essentially useless...

That's because you don't want to spend $400.

You modify your car?

You want the best performance?

You want it to be as close to legal as possible?

If YES to any of the above, that simply is the cost of playing cars.

That's because you don't want to spend $400.

You modify your car?

You want the best performance?

You want it to be as close to legal as possible?

If YES to any of the above, that simply is the cost of playing cars.

Yeah..I was kinda thinking the same again today..

I picked up a cheap jasma system now im just shitty cause its gunna cost me 500$ to get it happening...But thats modding, it could be worse. :(

Another thing i was thinking was i notice a few people have said the XR6 cat is good for 300kw..Im assuming its 3 inch, why would this not be a good option..I know its probably 400$ or dearer new but surely a second hand one could be found cheapish?

Well, the real test would be chucking the exact same car on the exact same dyno with the stock cat and then with each of these aftermarket ones, all other things unchanged.

I wonder what the real-world performance difference is between 428CFM, 570CFM and 706CFM cats (claimed or real, at whatever pressure drop) in a ~200 rwkw car?

I agree, the dyno would show any differences easily.

I've heard a general rule of thumb is 2.2CFM per HP. 200rwkw ~~ 280HP, 25% drivetrain loss ~ 370HP, times 2.2 is around 800CFM.

That's a very quick and dirty calculation, but even so.. a 428CFM cat will be causing quite a hefty pressure drop when you try and force 800CFM worth of air through it. That's probably for NA cars a turbo is more efficient at generating power so the metric might be 1.8CFM per HP (plucking a figure out of the air). If that was true you're now at 650CFM.

Well do you think a cheap one will be any good if all of them are around $400? :P

Hi, I'd like to buy perfection for a pittance. where do I sign?

Yeah..I was kinda thinking the same again today..

I picked up a cheap jasma system now im just shitty cause its gunna cost me 500$ to get it happening...But thats modding, it could be worse. :P

Another thing i was thinking was i notice a few people have said the XR6 cat is good for 300kw..Im assuming its 3 inch, why would this not be a good option..I know its probably 400$ or dearer new but surely a second hand one could be found cheapish?

XR6t cats have one inlet, two outlets. They would be even harder to fit.

I just bought one of the 4 inch 100cpsi metal cats, (fleabay special) for $150 its a pretty cheap upgrade. Slips over a 3 inch pipe.

2 outlets i see, that makes it definitely not an option for me then...

Hows the cheap cat working for for you? Which one did you get?

Sometimes a cheap upgrade can be a downgrade so im wary ,but also poor atm...I can get good deals on magnaflow cats but they only go up to 3 inches...

Edited by Arthur T3
2 outlets i see, that makes it definitely not an option for me then...

Hows the cheap cat working for for you? Which one did you get?

Sometimes a cheap upgrade can be a downgrade so im wary ,but also poor atm...I can get good deals on magnaflow cats but they only go up to 3 inches...

I bought a Loboka but a few seem to come from the same factory. Much higher flow than the 200cpsi on my old system (cost me a fortune) but I bet it doesn't work as well emissions wise. Im going for an accurate dyno run next week but its easily flowing 260awkw on my auto VQ25 running E85.

I made a 3.5 inch exhaust for a 2jz Aristo a while back, it had a similar 4 inch cat and I ran the 3.5 straight in to it. My tuner was happy to tell me it pulled 360rwkw with a gt3540iw. If a 100cpsi cat can flow that sort of power, they don't pose a restriction to exhaust flow.

I bought a Loboka but a few seem to come from the same factory. Much higher flow than the 200cpsi on my old system (cost me a fortune) but I bet it doesn't work as well emissions wise. Im going for an accurate dyno run next week but its easily flowing 260awkw on my auto VQ25 running E85.

I made a 3.5 inch exhaust for a 2jz Aristo a while back, it had a similar 4 inch cat and I ran the 3.5 straight in to it. My tuner was happy to tell me it pulled 360rwkw with a gt3540iw. If a 100cpsi cat can flow that sort of power, they don't pose a restriction to exhaust flow.

Thanx

Sounds good,i may have to give it a try if it lasts me 10,000ks thats only 2 years driving ill be satisfied and worry about a better one then..

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