This may sound cheezy but you can actually make a "bass tube" from a concrete form found at any building supply or hardware store. They come in all different lengths/diameters & are made of carboard(light) 1 end has the speaker & the other gets a port or ports & terminals. You want to add some kind of stuffing inside. Its pretty simple & cheap to make. Sits right down in the "trunk" with the amp mounted on top. T-tops still sit the way they were intended not with a speaker pounding against it. Most people think its 2 12's they are hearing & its only a single 10" sub running on 150watts
. I have tried this in other makes but the camaros & firebirds sound the best due to the rear glass.
the plate is a cheap way to go or cutting one yourself but if you have t-tops & keep them in the trunk you might crack one from the bass, seen that happen a few times & good t-tops aren't cheap:bandit: