My XTRONS is plug and play, it fits E39 straight away. i didn't need to trim the dashboard, i did need an extension cable from XTRONS though, cause my stereo connections are in the boot next to the battery. I have friends who have XTRONS radios as well. Never heard complaints from them. my unit is a PX6, it takes only a second to boot, very impressive. it makes my driving much more enjoyable.