I have the slug. A 5.9l magnum it's the long bed with 4x4 I have added a cold air intake didn't see much of a difference(at least 250000 miles on truck) I have put a magna flow exhaust on with no cat. Is that causing a back press. Problem? I would like to change the torque converter and and clean out tranny oil. Would a tb spacer be helpful or a waist of time and money? I'm also interested on if I go to a smaller diameter exuaghst will that build torque?

 

How's the plenum? Throttle body spacer will not do anything.

 

Cold air induction doesn't do anything either. The stock system is already drawing cold air from the fender, which is where most of the CAI systems get theirs as well.

TB spacer is a waste of money on a port fuel injected engine.

With 250K miles on it, it is more than likely just tired. Fix the plenum, do a full tune-up, replace the water pump/timing chain and gears, that will get you some power back.

Of course, doing a compression test to see what kind of shape the motor is in wouldn't be a bad idea.......

You really need to get the engine squared away, before doing other stuff.....

 

+1 to everything they have said.


Exhaust it's hard to say whether you need bigger or smaller as we don't know what you have though full 2.5" is generally considered good for low-mid-early high range and 3" for late low-mid-full high range.