Thanks for your inaccurate reply. If you take the time to comprehend my post, you will see that I was criticizing your lack of good judgment in coming on here(a forum, of which we have ample proof, is regularly monitored by Police)and advocating/downplaying the practice of "gutting" CAT's. We are trying to NOT attract undue surveillance or scrutiny, not to increase the possibility of being "targeted". Your comments concerning my supposed "burnout/drifting" at a Tech Day, are nothing more than fiction. In the 10 yrs that I have owned my Z32. I have NEVER performed a "burnout" or so-called "drift"(a sport which I personally loathe). BTW,the readiness to "report" the supposed "goings-on" at Tech Days, is one more reason why there has been a deplorable drop in attendance at NSW events/cruises(people don't want to lose their Licences).
Zeds respond really well to a good exhaust system....... good dumps, engine pipe, large cats, highflowing mufflers etc ALL improve power. Opening up one part of the system and not others wont make didly squat differance except to your wallet if your caught. Kingy
i gutted stock cats on a "track only" zed and was dissapointed at the lack of performance increase. so i would not recommend it. As for the fine, the 10k fine is the max penalty which i belive is only in teh case of a mechanic who has been caught doing it or admits to knowingly driving a car without a cat. Imagine the amount of cars on australian roads where owners are genuinely unaware that their car has a gutted/non functioning or absent cat convertor . It is highly unlikely in my mind that these people would be subject to a ten thousand dollar fine. Having said that, i imagine the powers that be would look on modified car owners in a different light and that ignorance is probably not a valid excuse. Either way its not worth it.
1-2% is definitely inaccurate... I'd say closer to 10-15%. Have a look at the cat. Look at the density. Of course with a lower density (High Flow cat) it will restrict a lot less... But the stock cats are actually quite restrictive. Removing or gutting the stock cats will yield a power gain if ur running a TT with higher boost. No doubt about it... Turbos will spool quicker and flow easier. Anyone who would like to question this theory, google it. However, it is illegal and high flowing cats and a better exhaust is the favourable option. As far as turbo seals go, if you are experiencing any smoke whatsoever right now due to turbo seals, removing backpressure will definitely amplify that problem. As mentioned in earlier posts, the seals will go downhill fast if they are already on their way out. Having said this, replacing your exhaust, dumps and cats with highflow items will also have the same effect... Am yet to find anything on the net even trawling Garrett's website looking for information regarding backpressure being required to sustain turbo seals. From what I have read, the less backpressure with a turbocharged vehicle the better. In summary, just make sure ur turbos are up to scratch before upgrading the flow of the exhaust in any way or form.
Im sorry but this is not the case, i did it on a boosted TT, with an excellent cat back and other bolt on mods and in very good tune. There was no performnce increase and i used to test the car regularly on the same dyno. The theory is sound but in practice it doesnt work, i think ti meands that there is another part of the stock front exhasut which restricts more than the cats.
Hmmmm, very strange... I have read other forums stating a fairly large increase in power with removing cats... 10-20hp in some cases... Although, this might not have been substantiated with any proof... I personally noticed a big difference going from stock front pipes/dumps to n-power front pipes / dumps... But that could be due to a number of things I guess... Cats could have been blocked/semi blocked, front pipes could have some sort of other restriction? Also, the n-power setup may be an improvement over stock... I guess just replace the whole exhaust and get some high flow cats to be sure. One more thing rollin, did you notice the turbos coming on any sooner? In theory, I would assume the less back pressure, the spool time should decrease?
im with you, i have seen big improvements on v12 jaguars and a list of other cars which is what pushed me to do it, but i was dissapointed, i put that in the box of mods i wouldnt bother doing to a basic zed again
I would guess that this is probably true. However, it would be based on gutting old cats which would be either partially blocked, collapsed or just not that free flowing. The same gain would more than likely be seen replacing these cats with good fresh high flow ones.
about a year ago i wanted to do the same thing but thought i should do some research first obviously illegal and i found that there were alot of stories getting about of coppers picking up on the funky smell then ordering a emissions test where if failed fines of around the 5k area were gifted. also the power side of things on a mild engine its going to make jack all difference and proven on dyno on modified cars to do a small amount. i know id rather leave them alone unless the colaypsed or become loose
its good you didnt gut them, but as for the smell, it doesnt happen , on idle a zed in good running order with no cats shows up at almost perfect emission on idle, its more at cruise and pwer that the cats work. Even if a cop was behind you and you booted it , he would not be able to tell, a stock zed drops the air fuel ratio to 10 to 1 which is mega rich, at that stage your getting black smoke and the cats are overwhelmed. The main ways they detect gutted cats are by driver admission or with a temp gun, stock cats are notably cooler when they have been gutted.
my cats were gutted on my previous setup with the highflow turbos as I was after every bit of hp I could get . but mine had a pipe straight through it so was like a straight exhaust with cat casing around it . that engine (RIP) didnt have a puff of smoke coming out it at high revs or any smell and at that power level there would be some real gains. not sure whether I'll run 100pci cats or not on new setup with E85
my CES dumps ran all the way to the cats and then straight pipe all the way through the cat . I definitely had a straight through 2.5 inch all the way where are the restrictors normally? built in the exhaust pipe?
Thanks for all the genuine help guys, wont be knocking them out now. May just go high flow if the time comes
