Different cats usually mean a different catalyst material/design. To get better emissions, the cats typically have to work more efficiently and hotter. The high-flow cats typically do NOT work as efficiently as the OEM cats, but flow more air.

 

Right, once you have a tune it will negate the factory set-up.
I also doubt any significant difference in the cats airflow (which is all that matters for performance).

 

You'd be amazed at the difference between a set of Magna-Flow high flow cats and the OEM high-efficiency cats

 

I have Magnaflow High Flow Cats on my F-150 and honestly they are not worth the money. The small amount of flow increase really is not worth it. I did not even gain a full 5HP by going to them. They do increase the exhaust noise but flow increase is minimal.

Richard

 

I have the direct-fit Magnaflow High-flow cats on my Crown Vic and they were a big improvement over the stock cats. Not only did the sound improve, but the low throttle and WOT response improved significantly. These were the direct-fit solutions (not some welding hack-job).

Ford doesn't play around if they use 2 different types of cats. The CA emissions package for the GT is going to have restrictive cats designed to operate more efficiently. The tuning is only part of the emissions package. Recall how the manual GTs have different mufflers from the automatic GTs. Again, Ford didn't play around. The mufflers are different and there was a price difference as well.

 

The mufflers are different for sound reasons, not performance.
Look it up.

 

Well mine are welded but calling them a HACK JOB is pretty Classless as on your part. But that's ok.

I went from 4 cats to 2 and the improvement was minimal. Most people that add mods are very reluctant to admit the mod was not worth the money. Not me I have no problem saving someone else money by revealing my mistakes.

Richard

 

 

I know that. Aftermarket axle-backs also have no effect or minimal effect on performance (without other exhaust mods). However, Ford doesn't fool around when it comes to using 2 different parts to do the same thing. If they spent the money to develop a CA emissions package, it'll be different. High-flow cats typically don't work as efficiently as OEM cats and will have a hard time passing CA emissions requirements. The CA emissions cats are going to be a bit more restrictive whether you like it or not. It's simple physics. You either add more extra efficient cats, or you use 2 really high-efficiency cats with a special tune. Look at the 99-04 GTs with 6 cats. Look at the S197s with only 2 cats.

I did not call YOUR welded assembly a "hack job". I've seen lots of "Magnaflow high flow cats" that are welded together and they're not the same thing as a direct-fit T-304/T-409 SS assembly. The OEM pipes used to connect the OEM cats are generally quite restrictive. The direct-fit Magnaflow assemblies used new T-304/T-409 tubing, at least for my application. I could definitely feel a difference in performance. Usually going from 4 cats to 2 cats on a Crown Vic will result in a louder exhaust, but the restrictions are generally further downstream (tailpipes and mufflers). Once you swap out mufflers, go to larger tailpipes (or no tailpipes), it will make a difference unless you have no other performance mods (cams, airbox, MAF)

 

Sorry but your assumption that High Flow Cats have a hard time passing Ca. Emmission is incorrect. Yes the readings are slighty higher than with the stock cats but they still perfrom well enough to pass the sniffer test without any issue what so ever. I have never had one problme with passing any of my smog check. It has also been prven that the Axle Back Muffler do indeed provide a small performance inscreas in the neighborhood of 5HP Again yes minimal which is what i am saying about the High Flow Cats. In my opinion the gain does not justify the cost.



Richard

 

The Federal emissions warranty is 8 years. Will the high flow cats still pass CA emissions 8 years after they are installed? That is the real question. As cats age, they don't work as effectively. The high-flow cats are a decent upgrade for those out of warranty and with busted stock cats. I wouldn't worry too much about the performance difference between a CA emissions equipped Stang versus a non-CA emissions Stang. However, if given a choice I would never put anything related to California on my car (other than the GT/CS rear bumper cover) just because I had bad experiences with CA emissions equipment on my previous cars (PITA extra BS components).

 

That I cannot answer. But i know of many Factory cats that do not last 8 years or 80k so that is not really even a fair comparison. I do however completely agree with you that This State Sucks when it comes to Emissions as well as many many other things.


Richard

 

All I know I am glad I don't live in CA. Not only do they have different cats, but just about everything that comes in a bottle, can, or box apparently causes cancer there

 

I very distinctly remember signs in San Diego near the Mexico border stating "No fruits or nuts". I found this very ironic since I was always under the impression that that basically described the majority of the population in CA!


Sorry dudes! I just couldn't resist. It IS funny how much different everything is in Cali. Must be a lot of bored lawyers...

 

I was joking, by referencing another thread on here asking if the 2007 mustang is slower than the 2005-2006.

 

That's right. If the car had CA emmissions--the dog left in the hot car for 4 hours wouldn't have died. Al Gore is very keen on curbing global warming and they are looking for any evidence that it is real.

The next thing you know spotted owls will fall out of trees and taste like Condors and Desert Tortoise'.

 

The dealer I bought my GT from is located in NH but is 15 minutes from MA. Because a lot of their customers come from MA (which has stricter emissions regs) every car they order gets the CA emissions package. It was almost reason enough for me not to buy a car there because I was concerned this emissions package would rob power.
I've no way of verifying whether or not this is actually the case but deep down I do think there is a difference. My tuner gave me an 87 tune and when he advanced the spark for the 93 tune, he said my car would not take the advance other S197's would. The result is my 87 vs. 93 tune yielded the exact same RWHP and RWTQ figures. Somehow I think the CA emissions has something to do with this. I really dunno really. I wish I did.

 

Did you go to Pete? He never said that about mine.

 

I don't really understand why they would order all of their cars with it, but it's free so who knows. Your tuning experience confirms that there are significant differences. For what it's worth, it's not mandatory for border states.

 

While it's not mandatory, the car dealer doesn't want to limit it's sales because so many people from MA, that does require the emissions package, buy their cars there. Many other FORD dealers in the same area don't order their cars this way. This one orders every car with it regardless.