Update CAR INSTALL.md

diff --git a/CAR INSTALL.md b/CAR INSTALL.md
index bdd40669eed0ae200cc10abfad562b81c9957cfc..38fbb55d6df3edb71d23fa1d1a2fb5f3db2425ac 100644 (file)
--- a/CAR INSTALL.md
+++ b/CAR INSTALL.md
@@ -44,6 +44,9 @@ The first thing to do on a Pi would be to use the `raspi-config` tool to expand
 # apt-get upgrade
 # rpi-update
 ``` 
+**Note:** if you are using a full-size Rapsberry Pi with the built-in DAC, it is a particularly good idea to update the Pi's firmware using `rpi-update` because, at this time of writing (September 2018), a [significant improvement](https://github.com/raspberrypi/firmware/commit/200c2f4dd54b2048b5dcb8661ea3f232beb7d81e) has been made to the [timing software](https://github.com/raspberrypi/firmware/issues/1026) of the built-in audio DAC's drivers.
+
+(Separately, if you haven't done so already, consider using the `raspi-config` tool to expand the file system to use the entire card.)
 
 ### Shairport Sync
 First, install the packages needed by Shairport Sync: