If I put a 4" exhaust on my truck. Will that allow my turbo to wind up, produce more boost, at a lower RPM? Or do I need to turn up the fuel pressure? or both?

 

it will help lower EGT's but I would not look for any kind of performance boost from it on it's own.

 

What are EGT's? And if the turbo is providing boost sooner than wouldn't that provide some kind of improvment?

 

It will help a little bit if the engine is stock, but other than the turbo spooling a little bit sooner, you won't notice much. However, the benefits will be more apparent when you add other power goodies.

 

EGT: Exhaust gas temperature

 

What exactly are the benefits of a 4" exhaust?

 

The biggest benefit is reducing the exhaust gas temperature, or EGT. Too high of an EGT, and pistons melt. The larger exhaust helps get the heat out of the cylinders faster.

 

Does that mean my engine will take longer to warn up? Also What would happen if I just increased overall boost. I have been told that the 12v stock engines can take it with out head upgrades.

 

More boost does not mean more power. You have to push more fuel and then you can see a rise in boost pressures above stock. Far as headgasket, I wouldn't push boost past 40 psi. Adding a 4" exhaust will help the engine breath better and lower EGt's as stated above. Search around this site and you will find a lot of the answers you are looking for.

 

You'll find many questions answered here> http://dodgeram.org/support_pgs/diesel_ix.htm