I am wanting to upgrade the stereo in my truck I have a 06 1500 mega cab with the infinity sound system. I have to space this out over time as I am working on a budget would it be recommended to replace head unit first or the speakers first?

Also does anyone have any experience with pioneer app radio 2 in these trucks and the sound quality it produces

 

Definitely replace the head unit first. An aftermarket deck will give way better sound than a stock stereo and should wake up those stock speakers just as long as they are not blown.