I do the same as Stealthwolf. I only have it running for around 10 seconds before setting off sometimes but I keep the revs very low, around 2,000 or less. I just make sure I always let it cool down, sometimes just for 10-20 seconds but if I do this then I'll have already pretty much been running on tick over for the last mile or so n not in boost.
Some people will obviously say that's wrong but it's just the way I do it and I've never had any problems in all the turbo cars I've had :)