Fruity Compressor
Fruity Multiband Compressor
Fruity Parametric EQ 2
Fruity Limiter
Maximus (especially Maximus)
These are, in my opinion, the best stock tools for mastering in FL. Compressor/Multiband Compressor obviously for compression, Parametric EQ 2 is a really good EQing tool, the Limiter to boost lower volume sounds while keeping the mix below a certain dB level, and Maximus is kind of like a do-it-all station that does the features of a lot of the other tools. I usually use all of these to some extent when I master, but Maximus is a good place to start if you don't have your own settings yet. Play around with the presets and find out what the different features do, there's a boatload of options in that
plugin
I also noticed the sudden volume drop in the saw. I'm assuming that you yourself didn't automate this, but the 808 sine bass that comes in takes up a lot of the headroom and lowers the other sounds in comparison. Mess with the saturation and the volume on the bass to get a clearer mix while still slammin. Right now your problem is that your 808 is simply way louder than the rest of the instruments, you can tell because when the 808 goes to a higher pitch everything becomes clearer for a split second then drops back down.
I hope I helped give you a sense of where you might start. I am by no means a mastering
expert myself, but this is just my knowledge and limited experience.
And don't get me wrong, I really like the idea of the track and the mix/master isn't that bad at all. Just felt like spewing out some tips