i used kitchen cabinet screws deck screws would work great, and as said t-nuts are always an option they wont spin unleass u over tighten them

 

I like these types.. particle board screw...yes predrill a bit first.
A good tip is to get scraps of 3/4 plywood and cut small blocks say 1" x 2" and glue them on the underside of the box to take the screws better. Or use them to put Tnuts in. 3/16 or #32 should be good enough. Remember you have to drill a hole in the wood that is larger than the screw to fit them. I then hammer them in. Sometimes you can put them directly into particle board. try it first.

one nice thing about using Tnuts is you can use fancy allen bolts...

 

might be tricky to install to mdf from behind but they sure hold nicely

 

I like these

 

Thanks for all the advice everyone! I went ahead and used number 12: 1 & 3/4 deck screws (had them handy here in the shop). They definitely grabbed the MDF better and pulled the sub nice and snug to the enclosure. Although they worked well those hex screws (pictured below) would probably look much nicer than the silver ones. Eventfully when I get my other sub I’m going to do the switch. Is it a bad idea to remove the current ones and go ahead and put the hex ones in, or should I just leave them now that they are in?

 

Those hex heads should have more meat on them than the deck screws.

 

2 words...duct tape...you can do anything with that stuff!

 

or .... ^^^^^^^^

 

weird.... this thread has the little symbol beside it indicating that I am subscribed but I'm clearly not. This is my first post on this topic. (glitchy)
oh well. since Im here Ill include my two cents.

These are the ones I use. and obviously pre-drilled hols.

Important thing to remember, Allot of people drill the screws in way to aggressive. After you pre-drill the holes,set the clutch on your drill so it does not over tighten and strip the MDF.
MDF splits very easily. Once you strip those holes your pretty much out of luck. gotta patch em and drill new ones in different spots which will force you to turn your sub to an angle. for a protectionist as myself, this will not due.
When people come to be with leaking boxes, 90% of the time its from poorly maintained screw holes.
Its not a race, set the clutch on your drill, if your drill does not have a clutch then I would just screw them in by hand. do it right, take your time and your box will last longer then you.

I make fiberglass boxes that run from $400 all the way up to $2000. when the customer comes to pick up there new box I often train them on this just in case they decide to remover the sub themselves at some point. You think Its just screwing in a few holes"how hard can it be"? but after you striped those holes in that 800 dollar box you'll be kicking yourself. trust me.

 

Duct tape Is awesome. there's no place for it in your car tho. or any kind of tape for that matter.