Flowing water sound...
 

I bought my 05 GT 8 a month ago, and have been noticing something that I find odd, and want to sooth my nerves if it isn't a problem, or take it to a dealer if it is.

When I first start the car, and when I first apply any light throttle, I hear the sound of running water/liquid, like someone is pouring a bucket of water over my engine. I check the oil level every gas fill up, and it is always between low and high, normally about halfway. I frequently pull out some, then get out and check the ground, and I don't have any leaking or draining, splashing, etc... I have checked under the hood, no fluids/dampness visible. I can only conclude that it is contained within something under the hood.

My 8 runs superb, 10,600 miles, but I want to know if this is something common or not, and if it isn't any guesses on what it might be to help let the dealer know what it is.

Check out this thread
https://www.rx8club.com/rx-8-discussion-3/fuel-pump-noise-131153/

I have the same thing let me know if you try the solution on the previous link there and if it works or not I've been wondering what that could be

Sounds good. I will certainly check that out. I will let you how it goes. It makes sense, since it is loudest after the longest periods sitting.