Front undertray
 

So mine fell off today.. thanks Midas for ripping off half the bolts and leaving the others half ass tight.

It's currently in the 40s. Any danger of driving with the undertray off until i find an alternative? Overheating?

Also what do you guys use for under trays?

Corrugated plastic or what should i look for?

I doubt you will have any overheating issues. I would have no problem driving the car as you normally do.

I use some bent up thin aluminum and galvanized steel.
I think it is for duct work, like in your house.
Zip ties and tape.

A brand new undertray is about $60 BTW.

I made mine out of super thin aluminum flashing that comes in 20" wide rolls and bolted it on using what I assume are the stock locations (the car came with no undertray so I can't be sure not it attaches)

I've removed mine when I was young and ignorant. I thought it was mostly for water protection X_x. No issues for 2 years and 4k ish miles but I'm I rarely drive in the rain.

No over heating so far but I found a used oem undertray for $20 of CL and am finally getting around to re-installing it.

Well my undertray never fit right after i dropped the radiator for the TD intercooler so getting a standard one is a bad idea.

If you are just looking to seal the bottom from the elements just grab some 1/8" ABS, trace & cut to the contours of your front lip and then run it far enough back to bolt to the front subframe nuts. Then do the same with the side panels(slightly harder with intercooler pipes in the way. A few rivets and good to go.