This question has probably been answered a gazillion times on here, but I can't seem to find it in the archives. I just bought a '99 3500 24v cummins, auto, dually QC LB w/ 110k miles on it. It has a U.S. Gear exhaust brake on it. I want to go to a 4" straight exhaust. Are there any other mods I need to do, and what will the exhaust brake sound like? Not looking to build a race truck, but love the sound and power of the cummins. Thanks for any help.

 

Just put it on and enjoy. Just a note also, if you get a certain power band that is too loud or annoying, playing with the tip length and diameter will change the band or eliminate it.

 

No other mods needed. But don't expect to gain horsepower with just an exhaust.

 

You may want to get a fuel pressure gauge to monitor the pressure from the lift pump to your injector pump. I'll be doing it to my truck here soon.

 

Exactly playing with the tip lenght and exhaust pipe diameter plays with the sound.The bigger pipe you go to then the quieter it seems well atleast to me it does.

Another thing you need to consider is getting pulled over for the extreme amount of noise you will make.

One day I was going up a steep hill south on 35 up onion creek parkway near austin in texas and I passed a guy driving an old volkswagon beetle with my loud 2500 straight piped with 3.5" pipe and I blew out his drivers window and so he must of got sort of disgruntled about the fact that i did and so he chased me down and they ticketed me with defective exhaust no muffler but let me go for the so called hit and run they claimed but because i wasnt aware it happened.No lie but i think it is bs how they conduct the law in texas.Too strict in my opinion . I Say no mufflers on diesels for all

 

If you thought you love the power and sound of T H E CUMMINS!!!!! lol then you will love when a pete 379 bull wagon speeding and loaded with a 550hp
cat gets up to you with your window down and downshifts throwing up the rpms and lets off with the jake brakes switch on high.You might have to change your drawers.haha,I had it done makes you even quiver a little.I prefer being in the big truck if you know what i mean.