Visiting your dentist can be a good thing. You keep your teeth healthy and you have a chance to source some neat tools (usually free) for use in your modeling workshop. Besides the picks and scrapers they use on your teeth ask about old bits and burrs they are discarding. These have a service life, once they get dull or worn they throw them away…well I’m not sure about that after my last visit. 
Here I detailed the exhaust stacks of the 1:48 Hasegawa F6F I am currently working on. I sanded flush the ends of the pipes, then using a drill bit in my pin vise I drilled a pilot hole. Using a dental burr, (rolled between my thumb and forefinger) I carved out the end of the pipe. This can be followed up with a larger drill bit to add additional depth, but thats up to you.
Hope some of you find this useful. When I add them to the model, I’ll take a pictures to show you how they look finished.