I literally couldn’t stand the sound of the stock head unit in the 135i so I fixed it. Put in a Sony unit I had from the totalled 328I that has everything I need (2 rca out channels, 7 channel eq, over 35w over 4 channels to the mid and highs, USB and aux I puts and low and high pass filters)
I don’t think it looks too bad, and I matched the colors to the rest of the dash lights.
The real reason for the head unit is to run an actual rca channel to my amp.
I have a DC Audio 2.0k and running 2 DC Audio level 3 12 inch woofers. Built the box myself to fit in the trunk of the 328i, and imagine my surprise when it fit perfectly in the 1s trunk. I’m running 1/0 Guage Knukonceptz wire and 250A in line fuses and a Stinger 1850W battery to take the strain off the stock battery.
The box is tube ported in the rear which basically turned the back seats into massage chairs.
So I’m super satisfied with the results. With the high and low pass set to overlap just a bit the small stock speakers are free to produce clean sharp highs and the Lil floor subs are basically mid bass drivers. The low pass sends everything under 120hz to the sub amp and it’s damn loud. Like stupid loud. I had to boost the highs a bit and cut the sub volume by half on the head unit to balance everything out and keep it clean. I hate hearing nothing but shitty bass like every donk there is.
The extra weight is a little noticeable, but everything will come out when I got to autocross obviously. The car is still plenty fast so i’de call it a successful day.