Better to wait until you have everything you need, to make the goal you want. My MPI, Pump, Sensors, Turbo, PM4 all went in at once. They weren’t purchased at once. I had a definitive pathway to follow and bought what I could as I could afford to.
^^This. My path was a little different, in that, I never thought I would get as deep on this platform as I have. I was going to be out of this car ('16 Golf R) by now and into an M2 but the used market is just so insane I'm sticking with my R for the next couple of years.
2.5+ yrs ago when I bought my R I "thought" I would be happy with just a JB4, downpipe and IC (that lasted 2 months).
After JB4 I went a custom EQT E40 tune and upgraded my HPFP (paid for 91 and E40 tunes). Great set up on stock IS38 turbo and lasted roughly a year.
Then upgraded to a Vortex and added LPFP and PM4 + 4bar PUT sensor and re-tuned (paid for 3 tunes). Car is currently on this and been running a little over one year. I've been very happy running this set up on the stock DI and have never felt the need to move to MPI until I did.....fast forward to now I just picked up 3 new tunes AGAIN with the Boost sale, ordered a Euro intake manifold, 5 bar TMAP from EQT. Will buy the Precision 925cc MPI kit when their BF sale hits and new lines.
Long story short---> I should have done all of this crap from the get go. I've now paid EQT for a total of 8 tunes when I could have just paid for 3 from the onset. I guess the one upside is I get to appreciate the incremental whp gains at each stage of progression.
In regards to your 400ish hp question--> If you do stick with stock fueling I believe with the Vortex XL EQT now recommends you at least upgrade your HPFP. If you do this along with upgrading at least to a 4 bar PUT (cheap) you will easily be at 400whp+ on 93 pump I believe you get in Virginia.