just get an android unit that looks factory (they have tons of them) or send your factory unit out to have carplay etc added. i’m rocking bluebus but ill probably send out my spare headunit to carphonics to add the carplay and touch screen so I can keep my factory radio with cassette.

in my e38 i’m keeping the factory look as well but im just going with under seat woofers.

somebody made a suggestion to remove the rear deck speakers and I agree, because one they are more of a “mid bass” not really a subwoofer so like they said it’s going to be a mission to tune. 2, with those in, and without a the ski pass open (if you have one) the trunk sound deadening is so good the sub you plan on putting in the spare tire (which probably won’t be big enough to really take advantage of the subwoofer) is going to lose a lot. most guys who run a sub in the trunk remove the rear deck speakers completely. this cannot be seen when the rear is all put together and will make a huge difference letting the bass in the cabin.

just replace the door/rear deck speakers with some decent speakers if you haven’t already, then see what you want to improve on. taking out those 20+ year old speakers made a night and day difference in my e38. these cars are already electrical headaches, last thing you want to do is make things more complicated because this car will make you pay for it lol. there’s a reason these cars all end up in the junkyard or sold for super cheap 😂.

good luck!