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Discussion Starter #1
well i got high flow cats put in my car and got new 2.5in piping from the headers back all the way to the 3.5in chrome tips *including my 6 month old flowmaster mufflers*..and i was wondering that if high flow cats have to be worked in like flowmaster mufflers...will it take a couple of months for the high flow cats to be more agressive?...it sounds so much *beefier* from 1600-3000rpm...my question is will it get louder with time since the piping is new from the headers back to the cats and that the cat arent worked in?....how long will it take if it does?..


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95' V8 LX
-Removed air silencer
-High flow cats
-Dual Flowmaster Exhast
-2.5in piping from headers to the back tips
-K&N Panel Air Filter
-245/60/15 yoko tires
 

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I wouldn't expect there to be a break-in time on new cats. Don't expect big performance changes with the exhaust setup - if you've seen the driver's side bottleneck collector you know what I'm talking about.
 

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Discussion Starter #4
Silver95Bird said:
I wouldn't expect there to be a break-in time on new cats. Don't expect big performance changes with the exhaust setup - if you've seen the driver's side bottleneck collector you know what I'm talking about.

huh?
 

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Discussion Starter #6
yea he told me that he wont touch them....it cant be removed?....i think one high flow cat with 2 mufflers would be fine...why wont anyone touch them?
 

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Discussion Starter #8
well if i got them off somehow and they were welded with jus piping would it throw off the car or not pass imissions even if i have a high flow 3rd cat and 2 flowmaster mufflers?...
 

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The best thing you did was ditch that stock set up! the computer will take a couple tanks of gas to compensate. Everytime you start it up it will go a little better. You just made a signifigant improvement to your cars performance. Pinging should be history at this point. Sounds a little better too, and I don't even have to listen to it.
 

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Sweet T
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Trust me when I say this. LEAVE YOUR CATALYTIC CONVERTERS ALONE. Unless you know somebody that is willing to be shady as hell on your smog checks, then don't touch them. Get a catback or something, gut the third cat if you must. But leave them in place. Every smog station I've ever been too looks under the car and they all know that the car is supposed to have 3 cats.
 

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porkchop2oo2 said:
A 2.5" exhaust system won't help when the exhaust outlets are 2" on the manifolds, and the driver's side pinches down to even less than that on the outside... the space the exhaust has to go through is smaller than the area of 2 of the head ports.




The diameter of the neck has to be about 1.8" on the inside, it's barely over 2" measured on the outside.
 

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You have a good point Silverbird. When Porkchop said from the headers back, I assumed headers were already installed. But from what I understand, aftermarket converters vary in length to compensate for the weight of the vehicle. Going one size larger in pipe diameter and using a cat for a heavier vechile, should work. The third cat, in my opinion, is just for noise and comfort. But if he has to keep it on I don't see why he could not use the Magnaflow resonator and still pass his state test. The key is to open the exshaust from front to back.
 

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Silver95Bird said:


A 2.5" exhaust system won't help when the exhaust outlets are 2" on the manifolds, and the driver's side pinches down to even less than that on the outside... the space the exhaust has to go through is smaller than the area of 2 of the head ports.

...The diameter of the neck has to be about 1.8" on the inside, it's barely over 2" measured on the outside.
YIKES DUDE!!!!!

One slip and you get rust all over those ford schematics. Watch Out!!!!
 

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It's okay they're printouts from my CD manuals... I can make as many as I want. :)
 

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Well, lets stop for a minute, and consider what youre exhausting.... Hot gas with some unburned hydrocarbons some 0xygen , and other foul stuff, all trying to expand and cool more...... now outa the exhaust manifolds, albeit small, and crude (I'm referring to the cast iron pieces on our birds)... so whats the objective? efficiency! Not Noise, which is unfortunately a by-product...Headers are worth 2=3 hp more on a modular unless you go for the big buck long tubes which they say will give you more power, but at what price? First downstream block is the cats, a ceramic honeycomb that the hot , expanding , or at least trying to expand gasses pass through....the heat causes unwanted , unburned particulate and gasses to burn when exposed to the catalysts, and that causes additional expansion, go figure,..... now a set of 2" -2 1/2''' pipes going downstream can handle that gas flow verry nicely with a couple low restriction mufflers... so where's the power?
I verry recently added a set of dynatech metal matrix cats for several reasons, and the initial choice was pretty good, but then I took the car to Ramsey's for a check/ retune on their dyno, and learned some interesting stuff;
1st... the RWHP went from 261.6 to 268.1 peak, no changes made, and AFR ok
only almost 7 rwhp gain
2nd...The RWHP up to 284.96, for a total gain of 23.3 rwhp after abit more
tweaking ....
I had a few other "issues that Mr. ramsey dealt with(i do not refer to him by his first name as that , 'dennis', leaves a foul taste in my mouth), but confused I asked where the xtra hp came from on the second pull, and he explained that the cats were probably pulling another 300 degrees heat out of the heads by flowing better, therefore the advance and fuel trim, etc could be tweaked more without risk of detonation, on a real hot and muggy day, and that gentlemen is the answer you need to look at..... as an aside, The boost is down to 5 lbs , or a tad less with these cats
 

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Discussion Starter #17
one word.........................whoa.........................whoa ^_^


_________________________
95' V8 LX
-Removed air silencer
-High flow cats
-Dual Flowmaster Exhast
-2.5in piping from headers to the back tips
-K&N Panel Air Filter
-245/60/15 yoko tires
 

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Leland,

That's why I wont touch my exhaust until I do the whole package. Headers, correctly sized and bent tubing, high flow cats... all as a system working together. Headers alone in front of stock cats probably wouldn't net very much, however with a proper exhaust behind them I think you'll see a bit more than 2-3hp change.
 

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Do the proper exhaust 1st... cats and all, dynotune,, and , .... Then stick on the headers... I will be surprised to see more than 10 hp with the long tubes , 4 hp with shortys... Be sure to get the Dynatech cats tho'... you'll love them
 

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You mean Dynomax Cats. That is what I have and they are cool… :eek:

Whats that 284.96 RWHP with a 5.4L? That can not be possible? You are close to A-Train when he had a tune at MM in the winter time. I bet you would match or exceed his numbers if you had the cool air he had? Funny he has been rubbing his SC numbers in my NA face for years now...

I have seen 4.6L SC with less ipower n the 12's... I am told that there is too much friction in that motor to have that much HP with just 6 PSI of boost.
 
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