Starting from v1.7 the installation process has been simplified and the go.sh script is not used anymore. Instead:

sudo mv /lib/firmware/intel/sof* some_backup_location/
sudo mv /usr/local/bin/sof-*     some_backup_location/ # optional
sudo ./install.sh v1.N.x/v1.N-rcM

The go.sh and install.sh for pre-v1.7 releases have been deleted, you can find them in the git history.

There is a single git branch now, everything is in the default branch.

You don't have to use install.sh, you can use any recursive copy of your preference. This is all what install.sh does, example with v1.7.x/v1.7:

cd v1.7.x
rsync -a sof*v1.7   /lib/firmware/intel/
ln -s sof-v1.7      /lib/firmware/intel/sof
ln -s sof-tplg-v1.7 /lib/firmware/intel/sof-tplg
rsync tools-v1.7/*  /usr/local/bin

If you don't want the symbolic links:

rsync -a sof-v1.7/       /lib/firmware/intel/sof/
rsync -a sof-tplg-v1.7/  /lib/firmware/intel/sof-tplg/
rsync tools-v1.7/        /usr/local/bin/

Remember that for rsync (and some versions of cp), a trailing slash in srcdir/ is roughly equivalent to srcdir/* + srcdir/.??* This is how a recursive rsync is always idempotent while a recursive cp is typically not.