Changing Mufflers on a cat c7

n4hwl wrote:
I have learned from experience with my Dodge truck (1998 cummins 5.9 isb) that when I added a 4 inch exhaust and a low restriction muffler that my exhaust temperature dropped some. I have a 2004 cat c7 in a 40 foot phaeton. I have the original exhaust and original air filter. I am wondering if anyone has tested the exhaust temperature change (if any) when going to a lower restriction muffler on these c7 engine in my type of application. Just wondering.

Ken

Ken,
Well Sir, I've changed the muffler on our '04 CAT C-7 and I'm going to tell you what I experienced. First off, the muffler I changed to is called the Aero 5050XL Stainless Steel muffler. It's a 5", straight through unit. I do not have an exhaust temp gauge, anywhere in line. So, that I can't help with. But, in all reality, I don't really feel any more power gain what so ever.

What both the wife and I did notice was one heck of a lot more NOISE! Our rig, an '04 Itasca Horizon, 36GD, has the CAT exhaust empty out at the rear, about a foot or so inboard from the right rear corner of the body. It's turned down and, blows towards the corner of the coach. So, in that, it's blowing the exhaust in a direct line, away from the driver.

So, you can't get any better in terms of directing the exhaust noise, away from the driver is what I'm saying. Now, "SUPPOSEDLY", one of the main benefits of this muffler is less back pressure which, is supposed to decrease exhaust temps and, again, supposedly, since there's less back pressure, the turbo is supposed to spool up earlier in the RPM range and therefore, you're AGAIN, SUPPOSED to get earlier torque than normal.

Well, I knew this rig pretty well before I installed it and, I've ran many of the same grades, towing the same weight, at the same temps, in the same conditions and, well, lets just say, for me, it was a waste of money. Others will argue and, that of course, is their choice.

In my personal opinion, because these rigs are so darn heavy and accelerate like a drunk dinosaur anyways, the only real and true test would be to put your rig on a dyno and get the readings. Then, install that type of muffler, WITHOUT DOING ANY OTHER CHANGES, and re-run the dyno and that, will tell you right then and there, if, there's any real change, other than NOISE!

Again, this is all my personal experience and opinion. Good luck.
Scott