I used some Infinity Kappa series 6.5" that I bought back in 1995 for my stereo comp car.
We just ripped out the old speakers and used some self drilling screws to attach them to the stock spacers.
We did not need any special spacers, and didn't use any sealant stuff.
I have two 10" DVC subs.. rattle from a door speaker is the least my worries!
Here is a before shot...
How did I even get sound out of this..
I bought 3 pairs of these for my comp car back in 1995.
They spend 5 years in my comp car at 145db, then that car died.
I moved them into my Impreza for another 9 years, then that car died.
Now 4 of them are in the SVX, and the other 2 are in my friends cobalt.
NOTE: NEW INFINITY LOW END STUFF IS LOW END AND DON'T LAST.
Which is why my friend is running a set of my old ones. His new ones died in under 2 years...
Shameless sell promoting begins here:
My stereo thread (Full of pics):
http://www.subaru-svx.net/forum/showthread.php?t=54516
Quick Video of the system: