I guess on an E91 the amp goes in the recess under the boot floor cover?
My hesitation is that because I have non RFTs, there isn't a lot of room in there (the amp looks quite big) - mostly taken up by the 12v compressor and Tyre Weld. I also have a made to measure Hatchbag so fitting it elsewhere in the boot isn't an option.
Apart from that, it seems spot on!
E91 335d SE Touring
Also Land Rover Puma Defender 110 XS station wagon