I used to have my fuel plate behind the stock position. My EGT's were running about what everybody else called &quot;normal&quot; (600* at 60 mph) and the cool down time was quite short. I slid my plate full forward and the EGT's were about the same but the cool down time was almost double. That I can understand. I bought a 15&quot; glasspack muffler and installed it to get rid of the drone. It is a 3&quot; staight throug muffler and worked like a charm for the drone. Now my EGT's are running about 500* or less at 60 mph. The pyro won't even go to 600* untill I am going up hill. If I get into it the pyro will climb just like expected. I have no loss of power and have seen boost as high as 32psi empty. I don't understand why the EGT's are running so low. Don't get me wrong, I'm not complaining. I just can't figure this one out. Any ideas???<br>ConfusedTom

 

Less back pressure? Maybe... ???

 

The engines not working as hard maybe. That's the only thing I can think of.

 

This may seem a little &quot;out there&quot; but here goes. From what I can understand there is somewhat of a turbulence in your exhaust. For example the perfect exhaust for our trucks would be straight out of the turbo without a single bend. If for some reason you had somthing in your exhaust that made turbulence or somthing the muffler may have helped by staightening it out or somthing. I know that the flowmaster muffler because of it chambers is not as good as a straight thru because of the turbulence it causes. Your glasspack has little &quot;fingers&quot; that stick in the airflow if your were looking thru it right? They may help the straighten the airflow. Anyone? :

 

Assuming your temp probe is pre-turbo, I doubt turbulence has anything to do with it. Most likely cause is lower backpressure.

 

Sounds to me like you hit the sweet spot for reversion tuning of the exhaust system. Diesels have an ideal length and diameter of pipe where they will generate a complementary sound wave that helps evacuate the burned gases.<br><br>Most of the Cummins 12 valve B series engines like a 4&quot; diameter exhaust about 83&quot; long. But, it sounds to me like you have hit upon an alternative that works very well for your truck.