Differences: Axle Back vs Cat Back?
 

I'm a bit of a noob when it comes to technical stuff like this, but what is the difference between the two?

-GDO

[quote][size=1][color=gray][i]Origami posted by [b]Onizuka[/b][/i][/color]
[font=Arial][color=royalblue]I'm a bit of a noob when it comes to technical stuff like this, but what is the difference between the two?
[/color][/font][/size][/quote]Axle back is a short section of pipe which goes from the rear axle to the tailpipe tips and includes the muffler somewhere in there. ;)

Cat back includes the axle back section above and extends further forward to connect to flange after third catalytic converter (3rd and final cat).

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0==[color=blue]WW[/color]==0
"…axles of evil…" - george w. bush[/color][/size]

[QUOTE=Wingless Wonder]Axle back is a short section of pipe which goes from the rear axle to the tailpipe tips and includes the muffler somewhere in there. ;)

Cat back includes the axle back section above and extends further forward to connect to flange after third catalytic converter (3rd and final cat).

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"…axles of evil…" - george w. bush[/color][/size][/QUOTE]

So which of the two should I get if I'm completely catless?

The Axle back?

-GDO

wouldn't you be looking at a complete turboback if you're catless?

I really have no idea what to get.

I have a completely catless down pipe paired up with my stock STi exhaust.

-GDO

[quote][size=1][color=gray][i]Origami posted by [b]Onizuka[/b][/i][/color]
[font=Arial][color=royalblue]I really have no idea what to get.

I have a completely catless down pipe paired up with my stock STi exhaust.
[/color][/font][/size][/quote]If there are no remaining cats on the car (STi?), then you probably want a cat back system to replace the stock STi stuff. As long as the catless stuff you have on the car retains the factory-type flange, most cat back systems on the market will bolt right up.

It also helps us identify what you drive if you fill out your User Profile a bit more completely. There are some differences between the WRX and STi exhaust systems.

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0==[color=blue]WW[/color]==0
"…axles of evil…" - george w. bush[/color][/size]

Sorry about that, the main reason I'm asking is because I'm interested in the purchase of the STi Sport Exhaust (Someone has one posted in the bay area forum) and then I was told I probably shouldn't get it because of my set up.

I'm really clueless now as to what to get. I just may stay stock if it's not worth getting.

-GDO

Ok just a short explanation of exhaust systems.

First off the lets start at the engine itself. The piping that connects to the four cylinders is the header.

Next is the up pipe which goes to the turbo (in the STI it is catless)

After the turbo is the down pipe which includes two cats

Then there is a mid pipe which is basically either a straight tube or stock it has a resonator to reduce noise levels (cat back starts here and includes the muffler)

The you will see the last and final piece which is the muffler (axle back starts here)

If you want to remove your cats you'd need to get a downpipe basically and i would certainly recomend a catback after that to complete the setup. The stock headers and up pipe on the STI are perfectly fine to my understanding. With the new down pipe you may see 15-30hp.

Word of caution: STI's are famous for boost creep with modified exhausts. On the top of this forum section is a thread dedicated to it. Start at page 1 the first few pages will explain it and solutions for it, the rest is just debates.

off subject but my last name is izuka.... :)

OT: Onizuka Air Field is in Mountain View, but it's now called Moffet Field again. Onizuka was the surname of the astronaut that died in the Challenger explosion back in the '80s. I think he was from the Bay Area or at least California, IIRC. Do you have anything to do with Moffet Field, Onizuka? Or is just your surname? :D

Anyway, to put in the simplest terms possible: the axle back is much shorter than the catback. The axle back is like its name: it's a pipe that runs from the rear axle to the exhaust tip. The catback runs from the last catalytic converter to the exhaust tip. The turboback runs from the turbo to the exaust tip.
Now some simple math: 1 turboback = 1 downpipe + 1 catback; 1 catback = 1 axleback + 1 midpipe. Therefore, 1 turboback can also be said to consist of 1 downpipe, 1 midpipe, and 1 axleback.
Get it? :D

.

These guys did a great job explaining it; but, here's a picture I think will help a little.

^^^
YES!!! That's perfect! +10 kewlness pts. for awns729 :D
Now I will *right click - save as*

lol, that kewlness points thing motivated me to do this: [url]https://www.i-club.com/forums/showthread.php?p=602621#post602621post602621[/url]

All the diagrams I've ever come across^^^^^

Oh man, that is a great picture. Ok, so I guess I need a cat back if I want to get rid of the resonator (will it make that big of a difference if I just get an axle back?)

I'm thinking I just want to get an axle back so I can keep the sound some what quiet still.

-GDO