# Cross overs in exhaust



## hm3to1stlt (Nov 8, 2004)

I have been looking at aftermarket exhausts for my car and I notice almost every package comes with some sort of cross over pipe. 

Is there something fundamentally better about taking away the "true-duals" from the existing system? I would think that that a true dual system has lower back pressure than a combine system.

What am I missing?


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## GTODan (Nov 9, 2004)

Having an H pipe or X pipe in an exhaust increases scavenging from side to side, i.e. a pulse going down one side creates a small vacuum that helps "pull" the next pulse from the other side. Also equalizes backpressure from side to side.


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## SJAndrew (Sep 28, 2004)

hm3to1stlt said:


> I have been looking at aftermarket exhausts for my car and I notice almost every package comes with some sort of cross over pipe.
> 
> Is there something fundamentally better about taking away the "true-duals" from the existing system? I would think that that a true dual system has lower back pressure than a combine system.
> 
> What am I missing?


A siamese pipe will aid in flow. True duals can actually worsen performance. GTODan is right (not many people know this fact).


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## GTODan (Nov 9, 2004)

Not true, ask any of my friends, I am always right


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## Monte (Oct 13, 2004)

Dual exhaust with a cross over pipe is better for performance.
One other misconception about performance exhaust is the 
pipe diameter. These big 3 inch pie systems are overkill for a small
block. Loud noise doesn't always mean better performance.
If you want to see some seat of the pants performance from an exhaust 
upgrade headers will make a mucher bigger difference than a cat back
system. I read in one of the posts that if you run your car with the
factory cat back system off , you only gain 4 rw hp. I dont think that
buying an $800 exhaust system to gain a portion of that 4hp isn't worth
it. 
There is another forum on LS7gto.com and some people were complaining 
about how loud the kits they bought made their cars.


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