AS mentioned already, you do not have MDS on your truck.

I installed a cherry bomb pro muffler and moved it back a couple feet to get it out from under the cab. Minimal drone, and I like it much better than the mbrp I had.

You're gonna be hell bent to improve mpg on that truck, but a cai def looks pretty. I just put a k & n in the stock box.

 

and efan will probly give you the most mgp gain but it is still minimal.

 

There anything preventative I should do for the truck?

 

Just normal stuff depending on mileage. Nothing really specific to the mega cab;
I would do all fluids for piece of mind, never know what previous owner did, or didn't do.