Been following this a bit.
This sizzle mentioned measurable or just your thoughts Claude ?
All of my muscle cars had steep gears and we're screaming pretty good at 80.
One of my lifelong friends gave me his old set when I moved here, the washer just went out and replaced it. I can no longer throw large appliances around to repair, I call for service like everyone else these days.
I did have a scraper used to aid in melting the rubber soundproof coating over GM air conditioning evaporator housings that were all too commonly replaced.
If you don't wish to disturb the neighbors, listen to elevator music at low levels or wife won't put up with it by all means buy something to support a set of bookshelf speakers.
You want impact and immersion you don't skimp where it's needed most.
2 ported 15s need something substantial.
Start looking at multiple 15s and up, horns blend nice.
Grand will getcha Minidsp, mic & 2 of the bigger Dayton audio subs. good start
Heard of Torx and Torx with the pin in center but never Tor-X. Something new or spelling error ?
If Ace or True value don't have it in stock they can normally get it.