Your asking for trouble, amp banging around, wires falling off and shorting out, twist ties breaking, and noises from the back when u hit bumps.

Mount that amp to a piece of wood thats secured to the car. If you dont have the tools or just cant figure it out go to any stereo shop and they will do it for 20-40 bucks.

yeah i think you are right I need to secure it better. I have some MDF laying around, but how do I secure that inside there? I am thinking maybe I could drill some holes in the mdf itself and loop some twist ties around throught the ventholes there.

NO TWIST TIES buddy. Screw, bolt or glue(not white glue) the mdf board to the vehicle then screw/bolt the amp to the mdf.

You should really just take it to ANY stereo place(bestbuy) and have them do it.

i love twist ties. j/k. I guess I was trying to avoid drilling but I have couple lag bolts and regular bolts that are up for the job. What is that vent for? Is it OK to block the thing?

The vent thing I think your talking about (no pic) is so the cabin doesnt pressurize when you close the door. Its ok to partially block it but try to give it at least an inch or two of clearance.