Just got my first Cummins
 

So it's taken a few years but I've saved my pennies and finaly bought a Cummins:5: As with any vehical that I’ve owned I want to make a few upgrades . Hoping that you all could help in a question.
1) What is the first upgrade that I should make? I am driving 100 miles a day with a mild load.
2) Who makes the best aftermarket products for the Cummins?

Edge juice with attitude, k&n cold air, straight pipe..