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Discussion Starter #1
I am currently in the market for an exhaust for my Z but I can't seem to make up my mind. I looked all over the forums looking for pictures, sound clips and reviews. I just had some questions and hoped to get some feed back so I can make in informed decision.

1. What the main advantage of true duel vs. a y-pipe setup?

2. Stillen, Borla, and other true duals except for Injen come together at one point, isn't it important to equalize pressure?

3. Does any one have any numbers or info on the Greddy system? (I've looked and I can't fin any thing but pictures and sound clips)
 

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http://www.carcraft.com/techarticles/69238/

Excerpt re: crossover pipes:

For any performance exhaust system, some type of crossover connecting the two sides of a dual exhaust system is important because it acts to balance the two banks of the engine. The common H-style crossover is good at balancing sound pulses between the two halves, but does little to promote scavenging because the exhaust gases tend to follow the path of least resistance, which is straight through each pipe rather than taking the 90-degree turn through the H-pipe into the other half of the system. In an X-pipe system, however, where the two sides of the system intersect, the gasses have no choice but to intermingle as they pass through the junction. This promotes improved scavenging effects by smoothing out uneven exhaust pulses from the engine’s firing order. It also helps quiet down the exhaust, resulting in a mellower, less raspy tone. According to Magnaflow, the faster acceleration of the gasses through an X-pipe causes them to flow in a linear fashion parallel to the walls of the tubing rather than tumbling. This “laminar” flowing gas is much quieter than tumbling gas, resulting in an exhaust tone up to 8 decibels quieter than a traditional H-pipe.
 

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You're right that Stillen and Borla mingle both banks of the exhaust and Injen does not. You can also add Invidia to the list of those who do not. Actually, Borla mingles the banks twice. They do it at their "H" Pipe and again in their muffler which is an X type that mixes both sides yet again. I've read what has been stated about the "H" and "X" and agree. Stillen is the only one that makes a system, to my knowledge with an "X". Stillen, however, is on my Never Buy A Thing From Them list.

I can attest to the advantages of the "H". I love my invidia, not to loud, very deep, and it looks great. It screams during acceleration and never drowns. I drove around on it for a week, and at idle, it felt sort of lumpy, hard to explain, but just not smooth.

I had my muffler shop weld in a stainless steel "H" Pipe, the sound at idle smoothed out, as well as the rough idle. The idle speed never changed, but it sounded better and felt smoother at idle. I was extremely happy with my decision. :) I'm glad I waited for this exhaust, and glad I added the "H". The exhaust is extremely well made, there is no chance for leaking, and the fit is fantastic. The workmanship is also excellent, and the thing is polished throughout. The tips are blue edged titanium.

Lou
 

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Discussion Starter #7
Right now I am leaning towards Greedy EVO 2 because its a true dull and I like the look of the two canister mufflers vs the sideways mounted muffler(s), but I still haven't found any information Greddy.
 
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