I put 22k hard miles on my 05 350z and never had an issue. then I had an 04 G35x I put 80K on and besides a faulty MAF that I was able to replace for $50, never had an issue with it either. I even sucked up about 2 cups of water, hydrolocked the motor, and was able to get it running again with no issues for another 15k before I sold it
Here's a crappy cell phone video of the water shooting out the plug holes as I cranked it over to get the water out the motor before throwing in new plugs lol.
http://www.youtube.com/watch?feature...&v=WcMePBd7yX8