1st of all, as far as accessories go for your truck, I already looked and there are many parts for your 02 Ram 2500 on one of my favorite websites www.summitracing.com you can go there an input the year make and model of your truck and they will show you what they have to offer.
Other good websites to check out are: JC Whitney, Jeggs, and xtremediesel.com also has a nice section for the Dodge Cummins trucks.
You can get a boost pressure gauge that you connect to a vacuum takeoff point on the inlet manifold specifically to check boost pressure, or inserting it into anothe vacuum line. This will give you the boost pressure in PSI. If you would like to know your current boost level at any given time while driving, I recommend installing a turbo boost gauge in your truck.
I am not sure what the stock PSI for a cummin turbo is, I have only worked on a Ford powerstroke turbo diesel, never a cummins, but if you cannot find it on the internet, calling the dealership or a local auto shop would be a safe bet.
As far as increasing your boost, you really needt o think about what you are doing first. Depending on how big of an increase you are looking for, you may need to install other parts as well to help handle the extra boost. With the stock turbo you can still get a good amount of extra HP an TQ with the correct modifications and an ECU tune and preferably a dyno tune after, but if you are looking for huge increases, then upgrading your stock turbo would be your best bet.
Some good companies for turbo upgrades are:
Garrett
FI Engineering
Turbonetics
Also check out Banks Power, Billydog Technologies, and AutoMeter