The factory Arcimoto speakers are made by Aquatic AV and are designed for hot tubs. The Polk DB 402 is a coax and has 3 times the woofer cone area, so has far superior response. I bought the speakers from Crutchfield, I recommend them as a dealer. Comparison photo here

You are first going to want to remove the side panels, and if you have doors, unbolt the fabric strap so that you have good working access.

The factory speakers have an odd mounting method. The grille easily pops off. Then you remove 3 machine screws. What is left behind is a metal ring. This ring is secured to the dash by two nuts which you will need to remove from underneath. Here is the ring, removed

The speaker has a quick disconnect for its connection to the amp. I cut the factory lead off and soldered it to the Polk supplied pigtails for an easier install of the Polks. Make sure you connect black to black so your speakers will be in phase.

Here is the opening you are left with

You will then need to lay out and cut the new mourning holes, which are slightly more than half an inch larger. There is some hardware underneath the opening so be careful of this while you are positioning your cuts. We used a dremel cutting bit for the main cutting, and finished with a dremel drum sanding bit. You will either need to make the hole slightly larger than the basket, or else cut notches for the clip nuts to clear. Here are the holes marked and cut. You will see a template that I made to make laying out the new holes easier

There isn’t much clearance to drill the screw holes, we did it by hand. Then you place the supplied clip nuts, then the speaker, then the grille, then the screws through the clip nuts. It is easy to jiggle the nuts out of alignment when you place the screws, so ensure they are threaded from underneath. Then clip the speaker wire socket, button up your plastic, and you are done.