Stick with the standard airbox. It's not a real bottleneck unless you're maxing out a k04, and even the 'best' aftermarket intakes come with some heavy compromises - have a read of the VWR intake thread. You'll probably lose some of that k03 response with any cone on a pipe too.
Stick a fresh OEM paper filter in the airbox, and put the money you've saved towards an uprated fuel pump. Loba or APR are the 'pre-built' options, and cost a bit, but you're buying reliability. The cheaper option is buying uprated internals to fit to your existing pump. VIS seem to be popular lately. Clinical installation is critical. Read up on it. An uprated pump gets more fuel in at low to mid revs where it's mechanically impossible with the standard pump. This is a massively underrated mod. Makes a big difference to 'foot down and boost hard' performance.
You don't need to 'uprate' the DV or PCV. Revision G/D and revision R respectively are proven.
Downpipe with decat / sport cat is probably the biggest gain, followed by fuel pump.
As for mapping, do your research but certain names like R-Tech, Revo, Unicorn etc are mentioned frequently for good reason. E-Tuners are making a name for themselves too.