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I have a stock '86 GT. A local guy is selling a 3 1/2" x pipe with the two flowmasters for a great price. I was considering installing behind my stock headers and back into the stock tail pips. I think the tail pipes a 2 1/4 but not sure. What are your guys opinions? and what cam should I get to go with the new pipes?
 

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Waste of time to have that big of exhaust only in the middle of the exhaust system with what I'm guessing is a relatively stock motor. And you don't buy cams to go with exhaust, you buy cams to go with motor combinations.
 

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Waste of time to have that big of exhaust only in the middle of the exhaust system with what I'm guessing is a relatively stock motor. And you don't buy cams to go with exhaust, you buy cams to go with motor combinations.
Lol...I was just going to say that is the first time Ive heard of some one trying to match a cam to there exhaust:lmao
 

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save your $$ and get a good 2 1/2 full exhaust.
 

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yeah 3 1/2 is a bit overkill lol, ur gonna lose back pressure and hp with a stock car...
 

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Backpressure is a myth. It does nothing for your car.

You actually do want to match your cam to the exhaust. But it's the collector of the header, not the x pipe or anything else. A cam matched to a collector will maximize scavenging in it's application.
 

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Backpressure is a myth. It does nothing for your car.

You actually do want to match your cam to the exhaust. But it's the collector of the header, not the x pipe or anything else. A cam matched to a collector will maximize scavenging in it's application.
I stand corrected then :)
 

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Discussion Starter #9
Waste of time to have that big of exhaust only in the middle of the exhaust system with what I'm guessing is a relatively stock motor. And you don't buy cams to go with exhaust, you buy cams to go with motor combinations.
I dont see how it would be a waste of time. I mean it would sound MEAN and that is what I am wanting, that a maybe a increase in fuel economy. I am already happy with the amount of power I get with my stock motor.:cool:

Lol...I was just going to say that is the first time Ive heard of some one trying to match a cam to there exhaust:lmao
Perhaps you haven't done much research on the subject.:mad:

stock car you'll go slower with that setup
I am having a hard time believing that. Maybe off the line, but it would open up the upper RPM performance. So your saying if I ran open headers it would hurt performance? hmmm even if I changed to the proper cam shaft?:no

yeah 3 1/2 is a bit overkill lol, ur gonna lose back pressure and hp with a stock car...
:noEven if its feeding back into the tail pipes that are 2 1/4. I don't see anything wrong with over kill, as long as it don't hurt performance.

save your $$ and get a good 2 1/2 full exhaust.
The guy is selling the 3 1/2 in pipes from header to x pipe to two flow master 3 1/2 mufflers all for $150. the back of the mufflers have turn downs but I was considering plumbing them back into my tailpipes to add a little back presure. I can weld and install the pipes myself.

Backpressure is a myth. It does nothing for your car.

You actually do want to match your cam to the exhaust. But it's the collector of the header, not the x pipe or anything else. A cam matched to a collector will maximize scavenging in it's application.
I'm not to sure about that. I mean backpresure does help with torque. At least on my Jeep motor it did. I always thought with open headers you wanted a specific cam shaft.
 

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If you look at backpressure as a restriction, yes, it can have it's place depending on the motor setup. There must be a certain amount of resistance to create the scavanging effect. A stock motor with 1 7/8 primaries and full 3 1/2 inch exhaust will not perform as well under all circumstances as the same motor with 2 1/2 inch exhaust. But with the right combo, backpressure is a killer. My 900rr's exhaust is a 4 into 2 into 1 flowing through a straight though muffler. No backpressure there other than the size of the pipes and length of the tubes in the 2 into one section. That's how it can do 13,000 rpms, but off idle (1100rpm) to 3k, it's a turd. It's what the cam was designed for.
 

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my car picked up 3mph pullin mufflers and runnin skinnys

do the math
 

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na wasnt specifically just my personal experience as a pro race car driver
 
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