Never heard of that happening. Our boat came from Tampa after being subjected to multiple hurricanes. It may have been pulled and put on the hard but I have my doubts. In any event ,water in the muffler was never a problem mentioned by the PO or surveyor..

Located In your port cockpit locker near/above the the antifreeze reservoir, you will see an anti siphon valve that prevents sea water from back flowing into the exhaust. Unscrew and remove the top from this upside down "U" shaped part and make sure salt hasn't built up and rendered it in operative. If it has, clean it with with fresh water. 

Siphoning risk is most prevalent when the boat is under a port heel traveling under sail at high speed.

I had a friend who owned a C34 and claimed if he didn't close down the water intake valve, sea water would sometimes flow into the muffler while under sail. I've never heard of that from anyone else and wonder if he actually had an anti siphon valve issue. I always sail with our intake open should an emergency engine start be needed. I've never had an issue. 

You don't mention if you are on a dock, slip or mooring, but closing all the thru hulls and making sure the bilgepump has plenty of power is a good idea in any storm. 
I'm guessing you are on the west coast with Hilary bearing down? If you can remove any canvas such as biminis, or at least make sure the jib furler has several wraps and maybe tie some docklines around the mainsail if it is still on the boat. For hurricane prep everything has to go but for 38 knot winds might not be necessary.

One hurricane thing that might be worthwhile is duct tape all around the edge or the hatches and ports to keep the heavy rain out. If you do that  remove the tape as soon as possible after the storm.
Good luck