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any one remove the converters from there pipes. min have been completely debaffled but i still want louder and if i do remove the converters do i need to install a diff map in my pc3
 

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You could probably cut open, gut, and weld-back the converters and get a smidge more sound but I don't think much, since the pipes still bend around there.

Truth be told, the stock pipes with the baffles removed are about as loud as it gets stock. You're best bet if you need it to be louder, is going to be a nice set of aftermarket pipes.

Whatever you do, whether aftermarket or cutting and gutting the cat, you will be changing the flow so you may need to change the map on the PC3. I assume, since you have the PC3, that you also have an aftermarket intake. (If not, then you don't even need the PC3 in the first place). If you're running a stock intake, you won't need to change anything, the stock intake is too restrictive to take advantage of the higher flow exhaust.
 

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If you're running a stock intake, you won't need to change anything, the stock intake is too restrictive to take advantage of the higher flow exhaust.
Forgive my ignorance. Why is stock intake and pipes so restrictive as they come stock. What is the reasoning behind it.... EPA?
 

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IMO you don't want to do both. The convertors on the 900 are in the first 3 inches of the mufflers. You would again IMO loose too much back pressure and thus loose torque in removing both the cats, and the baffles you'd be almost to straight pipes. Of course there is a baffle plate of sorts that is in front of the cat in each muffler as well. Man I should have took pictures while I had mine apart.
 

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Just FYI, back pressure doesn't create torque. I used to think that too until I read a very informative article on the subject. Torque is affected by small diameter pipes because friction of exhaust gasses on the exhaust pipe walls creates a suction effect, increasing flow at the low end. Larger diameter pipes don't have the suction effect but also don't produce back pressure at the high end, which is why they tend to have less low end torque but more high end horsepower. If I I find the article I'll link you to it, it explains it much better than I did.

As far as why they are so restrictive- I think it's a combination of EPA standards and fuel economy. Most people who do the big three have a slight drop in MPG. That drop might drop it below the MPG of some of Kawa's competitors!
 

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Just FYI, back pressure doesn't create torque. I used to think that too until I read a very informative article on the subject. Torque is affected by small diameter pipes because friction of exhaust gasses on the cylinder walls creates a suction effect, increasing flow at the low end. Larger diameter pipes don't have the suction effect but also don't produce back pressure at the high end, which is why they tend to have less low end torque but more high end horsepower. If I I find the article I'll link you to it, it explains it much better than I did.

As far as why they are so restrictive- I think it's a combination of EPA standards and fuel economy. Most people who do the big three have a slight drop in MPG. That drop might drop it below the MPG of some of Kawa's competitors!
Thanks for the great informative information. It all makes sense to me now.
 

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Just FYI, back pressure doesn't create torque. I used to think that too until I read a very informative article on the subject. Torque is affected by small diameter pipes because friction of exhaust gasses on the cylinder walls creates a suction effect, increasing flow at the low end. Larger diameter pipes don't have the suction effect but also don't produce back pressure at the high end, which is why they tend to have less low end torque but more high end horsepower. If I I find the article I'll link you to it, it explains it much better than I did.

As far as why they are so restrictive- I think it's a combination of EPA standards and fuel economy. Most people who do the big three have a slight drop in MPG. That drop might drop it below the MPG of some of Kawa's competitors!
You are correct on that and a good description of it also. However said "suction" can be caused by more than one facet, such as 2 into 1 pipes and also reverberation cones. But it its true that "backpressure" is not directly the cause of torque resulting exhausts. However it sometimes is a byproduct of the scenario.
 

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I know nothing as Sargent Shultz might say, but I do know the right amount of back pressure is important for performance. Take it all away and you get sick quick....
 

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I know nothing as Sargent Shultz might say, but I do know the right amount of back pressure is important for performance. Take it all away and you get sick quick....
I still think it has more to do with the shape and type of exhaust. Backpressure creating anything positive makes no sense. Backpressure reduces the amount of air (and thus fuel) that enters the intake because it doesn't allow the exhaust gasses to completely leave. There are a ton of factors regarding horsepower and torque, but both are increased when air and fuel are increased, that's how an engine makes power after all! Backpressure does the same thing as restricting your intake, and nobody thinks THAT makes power.

I'll admit I'm no engineer, but I was always perplexed by 'conventional' wisdom telling me that back pressure is necessary, or otherwise. I like to read and research, though. I also remember hearing that mixing synthetic and conventional causes oil leaks, but then I learned that in the old days when synthetics first came out, old oil seals would break down and pack in with grime. Synthetic oil found it's way around that and leaked. Backyard mechanics saw the fact that they had added oil, and the though of oil causing an oil leak didn't make sense, so they figured residual conventional in the engine mixed and somehow reacted and corroded something.

I wish I could find this article. They did all sorts of dyno tests, involving restrictor plates, different diameter pipes, different length pipes. All on the same late model V-8. In the end it proved what the engineer had already said, more backpressure = less power. Smaller diameter pipes = more low end torque due to what he called "Scavenging", but also a reduction in top end horsepower (and top end torque, because, whadya know, it was getting backpressure!)

He claimed the perfect recipe for low end torque was absolutely no back pressure, and a pipe diameter that allowed the particular pulse of the engine at the desired RPM (say 2,000 RPM's) to have the biggest scavenging effect, effectively creating 'negative' back pressure, or 'suction' in the pipes.

That article and everything I've read on the subject could be wrong. I'm no engineer. But I'm also not one to believe conventional wisdom or 'what we've always heard', I'm a need-to-know-why guy and when I needed to know WHY reducing the air and fuel in the engine created more power, I looked it up, and apparently I was wrong all along.

Anyway, my point being, I'm pretty convinced from all I've read that back-pressure does nothing positive and anything to the contrary is a myth. Like most myths, probably the result of poor observation. Smaller diameter pipes make more low end torque, so someone figured that means more back pressure, thus back-pressure = torque! But it's not the case.

It's amazing what stuff grandpa always taught ya that juuuust isn't quite the case. Usually a result of a mis-placed observation.

Edit: Unless you're referring to the issue of damaging the valves. That's due to heat. If you have really short (or no) pipes, you run the risk of cool air rushing in behind the valve when it closes, hitting a very very hot valve. Take hot metal and cool it rapidly, and you get cracks, warps, and all kinds of nasty stuff. The pipes we're talking about here though, are plenty long enough to keep the air around the valves warm. Again, in this case, it's not backpressure that protects the valves (once heard someone say with no backpressure valves slam shut and break, that's why you have to have pipes on- well that's not the case, it's the cold air that breaks them, even the most restrictive exhaust isn't going to affect the force by which your valves close) it's the heat the exhaust traps in around the valves.
 
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