I am brand new to anything diesel outside of a tractor. but I gutted my cat welded a pipe in place of my muffler, put k and n air filter, ts 6 pos chip. stretched the spring in my return valve(90 psi ) fuel. but no huge power gains. also when I had the cat off I cranked it to hear it and was supprised how quite it was. My f25o weighs out about 10,000 lbs with welding machine and service boxes full of crap. Help man

 

K&N filters are terrible. They dont flow enough for our motors. And hopefully it isn't an oiled filter, or it will dust the turbo and even the motor.

 

K&N's flow fine they just don't filter enough. So I would take that off and do a DIY intake. Im no expert but 90psi is a little much I have 65 going to mine now. You can all ways do a set of stage 1s that would help alot with power

 

That's a lot of weight for 230hp... All your mods gained you about 60ish hp over stock...

If you are running 90psi on your fuel pump, you are taxing it way too much... Get it down to about 65-70psi...

 

you said that the truck was really quite still.could your EBPV (Exhaust Back Preassure Valve.) be stuck shut iv herd of this happening and im sure that would prob make it loose power.

 

Thats true if the ebpv is stuck the truck will be gutless. Put your hand in front of the exhaust pipe; if the exhaust is barely trickling out and not completely blasting your, the ebpv might be stuck

 

if it is stuck, you should be able to hear it. is will make a sshhh sound.

 

Ya but if he cant hear the exhaust w/out the ebpv, he might not know the difference.