I had a set of Infinity speakers years ago. I was impressed with them for the money. They ended up in three different cars, owned by different people. They were robust. Wish I still had them, I was offered them back, but they got scrapped with the car. Anyway.

Nice little boxes you made there. Are they vented at all? I'd heard that car speakers like to be in open baffle to work at their best. Not sure how true that is.