Standard Cats

[chook]

Guys,

How restrictive are the standard cats on the VE l98. I have been considering exhaut options for what seems and eternity cat back, full syste,m etc and was wondering how restrictive the standard cats are. For example is it worth going headers with stock cats and a cat back? Juest seems that the cats are the expensive part of any system and if they flow ok why replace them??

[Wonky]

My guess is they're not bad for factory cats. Unfortunately I doubt that anyone has done full back to back testing on the L98 just changing from factory cats to high flows.

When I first got my car I had a set of GTS extractors and cats put on as initial testing had apparently showed they flowed pretty well. However, later on I went to Pacemaker 4-1s and KPM's mega cats and picked up 14rwkw. I have no idea how much of that was the 4-1s though and how much was the cats. I'm guessing probably 50/50???

I'm not sure whether the GTS cats are better than L98 cats or the same. If they're better than the stock L98 cats then there is even more to be gained than whatever I picked up in the cats change.

I know that doesn't directly answer your question, but there is almost certainly a gain to be had with high flow cats. The unanswered question still is whether it's a good BFB mod..........

[SSV8TE]

Gday mate,
When you have a look at a standard cat against a high flow you will spot the difference straight up. Using laws of physics the standard has a rightangle pipe into it and the highflow is straight through so the high flows must have improvement over standard. I dont have any proof of this but it makes sense to me and many others. Im sure there would be backed up testing somewhere on these forums. Probably worthless info but hope it helps some.

Cheers,

Andy.

[BLACKVE]

Just remember that a ve standard cat is 2 1/2" inlet/outlet but has a body around 6", think this helps provide good flow for a standard cat. No after market cat is EURO 4 emissions(VE onwards) legal either so were all driving around in cars that can be defected if they wan't to be pricks

[SSV8TE]

Just remember that a ve standard cat is 2 1/2" inlet/outlet but has a body around 6", think this helps provide good flow for a standard cat. No after market cat is EURO 4 emissions(VE onwards) legal either so were all driving around in cars that can be defected if they wan't to be pricks

Absolutely and too add to the controversy all of us with extractors are running around generally with way to high decibels out back too , depending on cat back of course.:bawl::bawl:

[badegg]

I hate cats hi flow cats are the way to go....

[chook]

I'm sure that high flow cats are the go but considering the outrageous price is replacing the cats going to give you that much more .
Approx $400 - $500 hundred a side is a lot of money that could be put towards something else after all.

Would short headers and std cats flow nearly as good, that is the question. Not to mentioned the new cats are the latest Euro ones which the aftermarket ones aren't.

Just wondering the Bang for $$$. Has anyone gone this route are we spending unnessesary $$.

[SSV8TE]

I'm sure that high flow cats are the go but considering the outrageous price is replacing the cats going to give you that much more .
Approx $400 - $500 hundred a side is a lot of money that could be put towards something else after all.

Would short headers and std cats flow nearly as good, that is the question. Not to mentioned the new cats are the latest Euro ones which the aftermarket ones aren't.

Just wondering the Bang for $$$. Has anyone gone this route are we spending unnessesary $$.

Gday mate,
I would think that when it comes to performance and flow , etc. the straighter the pipes on exhaust from the manifolds, extractors or headers out towards the back the better the flow will be so for every less restrictive corner or exhaust you remove the more performance. The standard cats are large in diameter but they still have a right angle that exhaust has to flow around. The aftermarket cats generally are straight through. So IMO i think you would have to gain a few rwkw's in changing to them. Overall every kw helps and as you move up the scale of mods im sure the percentage of improvement would increase also.
Cheers,

Andy.

[pauley]

Gday mate,
I would think that when it comes to performance and flow , etc. the straighter the pipes on exhaust from the manifolds, extractors or headers out towards the back the better the flow will be so for every less restrictive corner or exhaust you remove the more performance. The standard cats are large in diameter but they still have a right angle that exhaust has to flow around. The aftermarket cats generally are straight through. So IMO i think you would have to gain a few rwkw's in changing to them. Overall every kw helps and as you move up the scale of mods im sure the percentage of improvement would increase also.
Cheers,

Andy.

hI GUYS, i'M TOLD BY GENIE AUSTRALIA THAT ANY CHANGE FROM STNDARD REQUIRES REPROGRAM OM ENGINE MANAGEMENT?? COMMENT PLS
PAULEY

[Gen3Unistudent]

Chook, check out Sureflo thread. $170 each for high flow cats 100cpsi. I just bought a pair and their great.

Pauley, Tune would get the most out of your cats. But a PCM reset will do the job until you get a tune in future.

[SSV8TE]

hI GUYS, i'M TOLD BY GENIE AUSTRALIA THAT ANY CHANGE FROM STNDARD REQUIRES REPROGRAM OM ENGINE MANAGEMENT?? COMMENT PLS
PAULEY

Only time you need a code removed is when you change the position of the sensors which are near the cats. The computer for example reads say 700 deg at a sensor and when you move it further back say with the extractors and cats it may only read 600 deg so the dash throws a code and your engine light comes on. A tuner will teach the comp that this is ok and it wont come up again. This is not a big task. When i did my exhaust mine came up and my tuner got rid of it in 2 mins. Also wont cause harm to system as it just means your emmissions are a tad higher or lower than stock.
Best of luck mate and hope this helped.

Andy.