I kick the living shit out of my car and I have never had the turbo glow realy bright. Only a slight redness to it. Cruising will not cause it to glow. Only hard acceleration will do it and usually it takes a good few hard sprints before it will glow or a top speed run.

2 things will cause the turbo to glow excessively and that is excessive ignition retard, or excessively high exhaust gas temps through either a restriction or running lean.