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Discussion Starter #1
Ok, I have the V6, what do you think would be better, I have no cat, and I need to put on some new exhaust...
Stock, I think 2 1/4", 2.5" or 3"?


How much better would it be to put on 3", 2.5" then to put on just normal stock exhaust. I'm sure I'll go with 3" but I need to know if its worth how much I'll have to pay for it. And generally, how much did everyone spend on it, including labor.
 

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Eternal College Student
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dont get 3 inch piping. our motor is not big enough to need it that large. free-flowing is good, of course, but then there comes the point where, if there is no restriction whatsoever, it will begin to slow your car down. 2.5 should be perfect for you. 2.25 wouldn't even be bad, but 2.5 should be a good size
 

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Mine is 2.75" and its like right on that thin line between too open and perfect. I agree, avoid 3" unless u want the engine to perform worse and have that nasty, lack of back-pressure "gurgle" noise when u stop accelerating. Almost sounds like backfires but i know it's not. This lame kid with the non-turbo FWD 95 Talon has his at 3.0" and i swear it sounds like his car is farting whenever he gets off his gas and stops or coasts. Gross.
 

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Discussion Starter #4
Alright, so yesterday my flex pipe broke apart. What should I replace? I only have 130, but I suppose I could save up.
 

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Zoom Zoom v6 said:
Mine is 2.75" and its like right on that thin line between too open and perfect. I agree, avoid 3" unless u want the engine to perform worse and have that nasty, lack of back-pressure "gurgle" noise when u stop accelerating. Almost sounds like backfires but i know it's not. This lame kid with the non-turbo FWD 95 Talon has his at 3.0" and i swear it sounds like his car is farting whenever he gets off his gas and stops or coasts. Gross.
This one's been covered several times...there is not a 4 cycle engine that I know of that "needs" back pressure. It is not the lack of backpressure that causes you to lose power when you have too large of an exhaust. The power loss is due to the lack of velocity in the exhaust gasses. IMHO I would go with a 2.5 " exhaust at the most unless you're boosted or on juice. Personally I'm going to go with 2.25" so that I don't completely lose the bottom end.
 

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The Full Dong
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just get the 2.5

Works great. Being that you have no cat, do yourself a favor and get a GOOD resonator...IE a Magnaflow or Dynomax ressy. They are made to much higher standards than those knockoffs and use some kidna stainless steel mesh that is highly durable and will last. If you get bigger mandrel bent exhaust, no cat, and a straight through muffler you will get annoying rasp.
 

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as everyone else is saying, dont go with the 3in. Go with the 2.5 or 2.75. All I have heard from people with 3in exhaust on our cars is bad news. ust not enough back pressure. Just my .02cents

James
 

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mtxpse96 said:
as everyone else is saying, dont go with the 3in. Go with the 2.5 or 2.75. All I have heard from people with 3in exhaust on our cars is bad news. ust not enough back pressure. Just my .02cents

James
Like Backy51 said, its not a backpressure issue, its a velocity and accoustics issue.

Correct though, definitely go with 2.5 or 2.25.
 

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CustomMX6 said:
Alright, so yesterday my flex pipe broke apart. What should I replace? I only have 130, but I suppose I could save up.
Have someone weld on a new flexpipe. Should cost about 100 bucks.
 

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The Full Dong
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$100?

Get the flex pipe from ebay....much cheaper than any shop will charge you. I know spada on PT didn't even weld his one...just used clamps and its been that way for a long time with no leaks. You can always have a shop weld it in later.
 

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Radar said:
$100?

Get the flex pipe from ebay....much cheaper than any shop will charge you. I know spada on PT didn't even weld his one...just used clamps and its been that way for a long time with no leaks. You can always have a shop weld it in later.
Cool, never thought of just clamping it on. Works for me.

I cut the rattling metal ends of my flexpipe off soon after I got my six. Did about 40k miles like that no prob.
 

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Discussion Starter #12
OK, so its not my flex pipe, but the pipe right after it broke apart, so I just wired it together best I could lol So I'll just go new 2.5" after the flexpipe to whatever muffler I decide to get if I get another aftermarket one, I've had 3 or 4 lol
 

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CustomMX6 said:
OK, so its not my flex pipe, but the pipe right after it broke apart, so I just wired it together best I could lol So I'll just go new 2.5" after the flexpipe to whatever muffler I decide to get if I get another aftermarket one, I've had 3 or 4 lol
3 or 4 really? Which ones have you had and what are your impressions of them?
 

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some cars require bacpressure, if not it sucks the intake charge right out the exhaust port with out detonating....the 4.6 litre ford for ex. It has to do with the cam and the degree of rotation.
 

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drvITlîkUstôlIT said:
Could you please re-word that so it makes sense?
he meant the fresh air and gas, that hasnt combusted yet, escapes out the exhaust without ever combusting. idk how our cars are timed or whether or not that would happen,

what i do know is to not use 3" piping!! it'll KILL your torque. dont get more than 2.5" if ur getting manrel bent either, u dont have enough mods to need any more.

so did ur test pipe rust out or it it the little bit of pipe before the precat flange rust? u should be able to get that rewelded for not too much money. a shop might say something about ur test pipe though.
 

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The whole back-pressure myth came about from the carbed engine era. back-pressure does not make your engine run better, it's just that when you suddenly remove the back pressure you need to adjust the air/fuel mixture to suit. On a carbed engine it does not adjust the mixture itself, and will run lean/funny if you simply remove the exhaust system.

EFI cars will adjust themselves to suit the new exhaust after a short while, within reason.

Having said that, too big an exhaust will sound bad, and by changing the length and diameter ratios of the pipes you may wreck the tuned length aspect of the exhaust. Check this post...

http://www.mx6.com/forums/showthread.php?s=&threadid=70391
 

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Exactly, a friend has a cavi with absolutly no backpressure and liquid gasoline will drip out of his tail pipe from time2time. If the exhaust valve is open at the same time the intake valve is, and there is no backpressure, the air/fuel mixture will exit through the exaust port, sometimes combusting in the header(s), and maybe ruining your valves or header(s). I would like to keep a little backpressure because I know the 4cyl is not designed with a performance cam... Don't know how the V-6 will act though, guess it has the right stuff...
 

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y cant we delete our own REPOSTs any more?????
 

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The Anti Rice said:
Exactly, a friend has a cavi with absolutly no backpressure and liquid gasoline will drip out of his tail pipe from time2time. If the exhaust valve is open at the same time the intake valve is, and there is no backpressure, the air/fuel mixture will exit through the exaust port, sometimes combusting in the header(s), and maybe ruining your valves or header(s). I would like to keep a little backpressure because I know the 4cyl is not designed with a performance cam... Don't know how the V-6 will act though, guess it has the right stuff...

Scavenging the intake charge out the exhaust port is not caused by (lack of) backpressure. Cam overlap is a big part of it. Also, like Wes said, the O2 system will compensate. Your buddy's cavi has another problem. :shrug:
-Garrett

Backpressure isn't a "myth"...It can be a helpful diagnostic tool.

"Properly tuned" is a oxymoron for an exhaust system. Many different setups, coming from different ideologies even, can yield good results.
-Garrett
 
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