Axel Back Ex. Question.
05-08-2006, 10:33 PM
#2
5th Gear Member
Join Date: Jan 2006
Location: Florida
Posts: 2,398
RE: Axel Back Ex. Question.
The 2005+ GT's have a very good stock exhaust system. The pipe from the header down to the muffler is 2.5" in diameter leaving plenty of room for exhaust to flow. An axle back exhaust is just swapping out the stock muffler - which isn't restrictive as it is - with another muffler from the aftermarket. Since there is barely any restriction with the stock system, you won't see any, if at all, gains from swapping mufflers. All you will get is a different exhaust tone.
Now, if you change the pipes (The section from the headers to before the axle back) you might get some gains, but only if you change out the more restrictive catalaytic converters. You can either go with an Off-Road, or basically the deletion of the cats, or you can go with a high flow cat system. Though do note that removing the cats out of the picture is a no-no for emissions, unless you live in one of these states where that isn't a concern... but it's just a matter of putting in your old H-pipe once that time comes around.
Finally, there are headers. Shorty headers, which is what we have stock... can be replaced with aftermarket ones, but they don't have that great of gains over the stock. Long tube headers, which require a little more work, but have much better gains are another option you can go.
Hope this helps.
Now, if you change the pipes (The section from the headers to before the axle back) you might get some gains, but only if you change out the more restrictive catalaytic converters. You can either go with an Off-Road, or basically the deletion of the cats, or you can go with a high flow cat system. Though do note that removing the cats out of the picture is a no-no for emissions, unless you live in one of these states where that isn't a concern... but it's just a matter of putting in your old H-pipe once that time comes around.
Finally, there are headers. Shorty headers, which is what we have stock... can be replaced with aftermarket ones, but they don't have that great of gains over the stock. Long tube headers, which require a little more work, but have much better gains are another option you can go.
Hope this helps.
05-08-2006, 10:43 PM
#3
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Join Date: Mar 2006
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RE: Axel Back Ex. Question.
In a nutshell:
Axle back swap (AKA mufflers only) = Louder, but no HP gain to speak of.
Cat-back, is basically the same as the above, except it should remove a slight restriction from where the OEM tubes are crimped. HP gains are very slightly, if at all, better than the axle-back. (probably not worth the money)
Aftermarket X or H pipe, 'off-road' style (no Cats) = Louder and HP gain, but not legal for emissions. Will give you hassles due to messed up O2 sensor readings. You either have to deal with the "check engine light" or you have to buy "oxygen sensor simulators" to fix the problem.
X-or H pipe with High Flow Cats = Similar to the above, but the HP gain is not quite as much as the 'off-road' pipe. But, should be emissions legal in most places except California, and no O2 sensor problems.
Shorty Headers: about 5 HP gain over stock manifolds. (IMHO, not worth the money. They are still expensive, and have just as much labor required to install as Long-tube headers, but only a fraction of the HP)
Long-tube headers: This is where the biggest HP gain is to be had in the exhaust system. Reports vary, anywhere from 20-30 HP.
Axle back swap (AKA mufflers only) = Louder, but no HP gain to speak of.
Cat-back, is basically the same as the above, except it should remove a slight restriction from where the OEM tubes are crimped. HP gains are very slightly, if at all, better than the axle-back. (probably not worth the money)
Aftermarket X or H pipe, 'off-road' style (no Cats) = Louder and HP gain, but not legal for emissions. Will give you hassles due to messed up O2 sensor readings. You either have to deal with the "check engine light" or you have to buy "oxygen sensor simulators" to fix the problem.
X-or H pipe with High Flow Cats = Similar to the above, but the HP gain is not quite as much as the 'off-road' pipe. But, should be emissions legal in most places except California, and no O2 sensor problems.
Shorty Headers: about 5 HP gain over stock manifolds. (IMHO, not worth the money. They are still expensive, and have just as much labor required to install as Long-tube headers, but only a fraction of the HP)
Long-tube headers: This is where the biggest HP gain is to be had in the exhaust system. Reports vary, anywhere from 20-30 HP.
05-08-2006, 10:51 PM
#4
The Paranoid One
Thread Starter
Join Date: Apr 2006
Location: Texas
Posts: 5,320
RE: Axel Back Ex. Question.
Hrm well what I was hoping to do was make the car a little louder.. and deeper.. and up HP even a little if thats all it did.
If I decided I didnt want to up the hp and just the sound.. that would mean replacing whats on it now and then losing some hp then... correct...?
(just going to a muffler shop for pipes). Theres some muffler shop here in town where all they guys go to put on pipes to make their cars or trucks (mostly) sound louder... is that the same part that you are talking about when you say pipes?
Without doing the no-nos... what should I do ?
If I got some axel backs I would leave the hp the same but sound increase correct?
BTW whats the diff between axel backs and cat backs and what do they do?
One last set of questions... whats involved with doing long tube headers?
Whatever I do I know a shop will do it for me..
Will long tube take the every day driving car out of it for me?
How much cash am I looking at there?
Basically Im looking for the best way to get a some more HP and sound without cutting corners and doing something that is a nono and trying not to spend just a fortune doing it.
If I decided I didnt want to up the hp and just the sound.. that would mean replacing whats on it now and then losing some hp then... correct...?
(just going to a muffler shop for pipes). Theres some muffler shop here in town where all they guys go to put on pipes to make their cars or trucks (mostly) sound louder... is that the same part that you are talking about when you say pipes?
Without doing the no-nos... what should I do ?
If I got some axel backs I would leave the hp the same but sound increase correct?
BTW whats the diff between axel backs and cat backs and what do they do?
One last set of questions... whats involved with doing long tube headers?
Whatever I do I know a shop will do it for me..
Will long tube take the every day driving car out of it for me?
How much cash am I looking at there?
Basically Im looking for the best way to get a some more HP and sound without cutting corners and doing something that is a nono and trying not to spend just a fortune doing it.
05-08-2006, 11:05 PM
#7
5th Gear Member
Join Date: Jan 2006
Location: Florida
Posts: 2,398
RE: Axel Back Ex. Question.
Most axle-back system won't really lose or gain anything.
Long tube headers will run you upwards of $500 for various types. Install depends on your shop, but would imagine that would be a couple hundred of dollars too.
Long tube headers will run you upwards of $500 for various types. Install depends on your shop, but would imagine that would be a couple hundred of dollars too.
05-08-2006, 11:21 PM
#8
1st Gear Member
Join Date: May 2006
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Posts: 62
RE: Axel Back Ex. Question.
It was mentioned that replacing the stock pipes from the headers to the axle-back is not emissions legal, but does replacing the headers result in more emmisions? i have to be concious of what i do to my car now, as i will move to Cali soon.
05-09-2006, 12:18 AM
#9
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Join Date: Mar 2006
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RE: Axel Back Ex. Question.
"Pipes" is a catch-all term for a lot of things. Most of the time when someone says "pipes" they're talking about the mufflers and the associated tubing.
If you change out your mufflers (same thing as axle-back, just a different name) then your car will be louder. Your HP change will be zero: no loss/no gain
Headers cost anywhere from about $500 to $1200 or so, depending on what brand you get and how they are made. Cheaper headers are made ordinary steel that is painted. The paint will burn off over time and the pipes will rust. Better ones are steel but have a ceramic coating. The ceramic coating is a lot more durable than paint, and it also helps trap heat in the header, which is good for performance. The best headers are made of stainless steel, which is rust proof and its naturally low heat conductivity does the same thing as the ceramic coating. Performance-wise they are all very similar, the only difference is how long they last and how good they will look after some time has passed. You also have to factor in the cost of installing headers. I would figure a couple/few hundred $$$ for the install. It is not difficult, but it is very labor intensive. Headers will not affect the "drive-ability" of your car. They just add HP.
To quote myself from an earlier post:
...if you are moving to Cali, then ANYTHING you change on your exhaust system would make you techncially illegal. The law basically says "you cannot ALTER the emissions or exhaust systems period". The only exception are parts that have a California Air Resources Board exemption (CARB #).
OH and if I say screw it and go with some axel backs for sound will I lose any HP over the stock ex I have?
How much is it to do the headers anyhow?
To quote myself from an earlier post:
Are headers legal? That's a tough question, it depends on what you're asking. Longtube headers are certainly no more or no less legal than short-tubes. The key is that you're changing the exhaust system of your car. It doesn't matter HOW your're changing it, the simple fact is that you are changing it. That's what will get you in trouble according to the letter of the law. The only way to stay 100% legal, according to the letter of the law, is to leave your exhaust system completely 100% stock, or to use only those upgrades which are CARB certified as OEM-replacements, which are few and far between.
Practically speaking though, the only way you'd have legal trouble with your exhaust would be if you had something that was obnoxiously loud and you pissed off the local cops, or if you failed your inspection/smog test. You **** off the cops if you have a very loud exhaust and/or you drive like an ***. You fail the smog test if you take out your cats. So, if you you run mufflers and cats your chance of getting busted is pitifully low, regardless of your headers/H-pipe.
The Dynatech kit that I bought has (high flow) catalytic converters. Cats are expensive, but it means you don't have the smog test hassles. If they do a visual inspection, they will look for cats. Or, if you live in an area where they do a tailpipe test, then you will need cats to pass. The other option is to buy an "off road" X-pipe or H-pipe, and then swap in your OEM pipe (with the cats) whenever you have to get an inspection.
Headers will alter the sound of your exhaust somewhat, but it's subtle. Loud exhaust or resonance has very little to do with the headers. Resonance or obnoxious noise levels come about when you change your cats or your mufflers. H/X pipes or headers won't affect sound levels very much, so long as they'e not also deleting/changing the cats.
It has been documented that the OEM mufflers flow extremely well, and aren't a problem until about 500+ RWHP.
That being said, you change your Headers and Cats if you want HP. You change your mufflers if you want sound. Replacing your mufflers (cat-back or axle-back) doesn't gain you an appreciable amount of HP. You could put in headers with your stock mufflers and your car would sound pretty close to stock...but you'd have some good HP gains to show for it. On the other hand, you could keep your stock manifolds and install just mufflers (or axleback)--in which case you'd be louder, but would have no (or very little) HP gains.
Practically speaking though, the only way you'd have legal trouble with your exhaust would be if you had something that was obnoxiously loud and you pissed off the local cops, or if you failed your inspection/smog test. You **** off the cops if you have a very loud exhaust and/or you drive like an ***. You fail the smog test if you take out your cats. So, if you you run mufflers and cats your chance of getting busted is pitifully low, regardless of your headers/H-pipe.
The Dynatech kit that I bought has (high flow) catalytic converters. Cats are expensive, but it means you don't have the smog test hassles. If they do a visual inspection, they will look for cats. Or, if you live in an area where they do a tailpipe test, then you will need cats to pass. The other option is to buy an "off road" X-pipe or H-pipe, and then swap in your OEM pipe (with the cats) whenever you have to get an inspection.
Headers will alter the sound of your exhaust somewhat, but it's subtle. Loud exhaust or resonance has very little to do with the headers. Resonance or obnoxious noise levels come about when you change your cats or your mufflers. H/X pipes or headers won't affect sound levels very much, so long as they'e not also deleting/changing the cats.
It has been documented that the OEM mufflers flow extremely well, and aren't a problem until about 500+ RWHP.
That being said, you change your Headers and Cats if you want HP. You change your mufflers if you want sound. Replacing your mufflers (cat-back or axle-back) doesn't gain you an appreciable amount of HP. You could put in headers with your stock mufflers and your car would sound pretty close to stock...but you'd have some good HP gains to show for it. On the other hand, you could keep your stock manifolds and install just mufflers (or axleback)--in which case you'd be louder, but would have no (or very little) HP gains.
...if you are moving to Cali, then ANYTHING you change on your exhaust system would make you techncially illegal. The law basically says "you cannot ALTER the emissions or exhaust systems period". The only exception are parts that have a California Air Resources Board exemption (CARB #).
05-09-2006, 12:37 AM
#10
The Paranoid One
Thread Starter
Join Date: Apr 2006
Location: Texas
Posts: 5,320
RE: Axel Back Ex. Question.
Im not in Cali.. Im in Texas. West texas.. I think Ill go by the muffler shop here.. which my bud says does all ex. and ask them about it..
If I do get it done, it will be done in a shop so I guess the first step is to see if they would even do it.
My bro tried to get them to do something with his glass packs on his truck which was illegal and they wouldnt do it...
So Ill see what they say about this.
If I do get it done, it will be done in a shop so I guess the first step is to see if they would even do it.
My bro tried to get them to do something with his glass packs on his truck which was illegal and they wouldnt do it...
So Ill see what they say about this.