Audio
The audio in my cockpit is still done by an old school Logitech Z5500! I've had it for over 15 years, and it is still working fine so I've just never needed to replace it. I wear a headset in the cockpit for DCS-SRS comms, and a bass shaker in the seat as well, so all it is really doing is ambient engine noise (and constant RWR beeping).
I originally had the speakers resting on top of the projection screen, but to make it a bit cleaner I decided to wall mount them. I hated the dated look of the units mounted on the wall, so I considered buying new ones altogether. After googling a bit, I found someone who had re-boxed the speakers, so I decided that rather then spend money on new speakers I would try that out first instead.
The boxes are made from 18mm thick MDF, ported at the rear, and are the exact same internal volume as the original plastic housings. Pretty simple to make, and I actually heard an improvement in the sound. But again, im no audiofile, and its likley just biased because im justifying hacking them up to myself...
My wife was not home on this day...
Cheap eBay speaker grills. Looks like a bought one (if you dont look too close).
Only four were modified and roof mounted, one in each corner of the room. The centre channel speaker stayed stock, and is mounted to the rear of the MIP, firing upwards.
kicking butt
Vibration in the seat is handled by a Buttkicker Gamer 2. This is a bass inducer/shaker. I originally had is hooked up to the subwoofer out, but the result was just constant shaking.
I later bought a very cheap USB soundcard and using Simshaker software it now runs completely independant of game sounds. The software gets data from DCS, and when an event happens it runs a seperate sound file for that event for the second soundcard only. 1000% better. For example- gear down, three seperate clunks felt in the seat when they lock down. Epic. Read more about that here.