I love the look of a dual exaust on a Jeep but don't want anything louder than stock. Are there any good dual exaust kits out there that don't get louder?

 

I don't think any company is going to make an exhaust that offers dual outs but no increase in sound or performance.

 

Weld on a fake exhaust tip.

There is no performance advantage to dual exhaust outlets on the JK, in fact most if not all of the after market dual exit exhaust systems will reduce performance.

 

How on Gods Earth could a dual exhaust reduce performance ?

 

OK, you asked.

Exhaust systems are all about maintaining velocity, retaining exhaust gas temperatures, scavenging spent fuel from cylinders and a smooth flow of these exhaust gases out the tail pipe. For any given amount of power there is an appropriate diameter of pipe. Running a smaller pipe than optimum inhibits exhaust gas flow and a larger pipe will reduce scavenging. Losing exhaust gas temperature will cause the exhaust gas to contract and therefore slow down, reducing cylinder scavenging (the more dirty air I get out the more clean air I can put in).

The biggest place for heat loss in an exhaust is the muffler. It acts as a large heat sync reducing exhaust gas temperatures at a greater rate than any thing in your exhaust system. Therefore it also slows down exhaust gases more than anything in the exhaust system. Now take this big heat sync that is already slowing down exhaust gases and double the amount of exits, with most often from the exhaust manufacturers 2 2.5" tailpipes where there was only a single 2.5" inlet. The only way to keep the same efficiency is if the two tailpipes have 1.75" diameter and that certainly blows the cool factor for anyone buying one and the manufacturers that sell them.

I hope that helps.

 

Ok we are talking cat back systems. My experience is that a naturally aspirated motor needs some back pressure which the cats provide. On vehicles with power adders such as turbos , blowers, Superchargers that they provide the back pressure needed. Also the cats are the hottest place in a. Exhaust system to burn up the unused fuel. I agree with the flow dynamics of not reducing pipe diameter. But there is no way possible of a properly designed dual exhaust of losing power.

 

Unless you are talking straight pipes with no restriction. Then I agree there will be power loss got to have some back pressure.

 

Anyone with Gibson dual cat back noticed that they're lost power?
Thats the one i was gonna get...

 

Everybody on this forum that's tried duals has said they lost power. Some have even changed back to a single.

 

The operative words here are properly designed exhaust system. You can't find a dual exit exhaust system amongst the after market manufacturers for the JK that is properly designed. Again, because it doesn't have cool factor and more often than not people buy these things for the sound they exhibit as opposed to the performance they exude.

The term back pressure is loosely used here and in other forums. It isn't about back pressure, but exhaust gas speed and volume. There is a balancing act between the two, but it's never really about creating back pressure.