Exhaust: Need help understanding how something works/functions

fox1x

New Member
Oct 3, 2005
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Northwest Ohio
I've heard that the '05+ exhaust systems are a big improvement over the previous years. (Sound better, flow better, etc.) I've been looking at exhaust and realize that there are "axle-back systems", and there are "cat-back systems."

Now, I do understand what the difference between these two products are, what I don't understand is what's the added benefit of the cat-back system over the axle-back on our cars? It seems logical to me that the difference is in the muffler anyway, so what advantage is there to buying the extra pipe that runs to the cats? (I also realize [think I do anyways] the difference in x-pipes and h-pipes, I just want to focus on the acutual systems)

For instance here is an axle-back: http://www.partshopper.com/shop/MAC-SS-Mustang-Axleback-Exhaust-2005-2006-2007-GT-m120.html

And here is the cat-back: http://www.partshopper.com/shop/Magnaflow-Mustang-Exhaust-System-2005-2006-2007-GT-m28.html

I know they are different brands, but I was just using these as examples to help illustrate my point. The only benefit I see that the cat-back system has is that it's manderal bent. I haven't looked under my car, so I'm not so sure that the stock system isn't manderal bent. Can anyone help me understand why I should buy one over the other? And, if one is better, is the added cost difference make the purchase worth it? Thanks.
 
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the stock exhaust is mandrel bent, but it does have a slightly flat spot above the rear axle. most people agree that it is not worth the extra money for a complete catback system. there are some that claim the catback is better, but no dynosheets are coming to mind where they proved it. the stock exhaust flows pretty well as it is, so there are not huge gains to be had when replacing the pipes or mufflers. another point that has been brought up about the catback is that some of them eliminate a few bends in the pipe, allowing easier flow.

IMO, stick with axleback.
 
Ahh thank you bigcat.

This is what I had been wondering. I really didn't expect "big" gains, I was mostly geting the exhaust for the enhanced aggressive sound! :)

I figured that there could not be gain from the complete system, but, I've been wrong many a times before.
 
the stock exhaust is mandrel bent, but it does have a slightly flat spot above the rear axle. most people agree that it is not worth the extra money for a complete catback system. there are some that claim the catback is better, but no dynosheets are coming to mind where they proved it. the stock exhaust flows pretty well as it is, so there are not huge gains to be had when replacing the pipes or mufflers. another point that has been brought up about the catback is that some of them eliminate a few bends in the pipe, allowing easier flow.

IMO, stick with axleback.

+1
 
here is a pic of the said flat spot.

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I have looked at my factory exhaust twice now when it's been up on a lift. It is by far a HUGE improvement over any of the other body style's systems! Bigger pipe from front to rear and is now all mandrel bent as BigCat stated. Biggest gain in power over stock on these S197s systems is by changing the headers.

BigCat, would you say to get good equal lengths to match the Pypes O/R H or get all new and go long tubes????
 
I have looked at my factory exhaust twice now when it's been up on a lift. It is by far a HUGE improvement over any of the other body style's systems! Bigger pipe from front to rear and is now all mandrel bent as BigCat stated. Biggest gain in power over stock on these S197s systems is by changing the headers.

BigCat, would you say to get good equal lengths to match the Pypes O/R H or get all new and go long tubes????
Tests have shown no gains of over 5-6 hp on shorties. Longtubes with cats give gains in the range of 20-25 rwhp with a retune. I gained 16/100ths in the 1/4 mile without a retune on JBA Longtubes with cats.