[68ragtop]

I have started my engine many times throughout the last 2 years putting the car together. almost always spitting water. Had the car at the muscle car nationals last November & dripped a few drops on the display mirrors after setup. So two Sundays ago I drove the car for the first time on the road. could not resist stomping the pedal down once coming out of a roundabout in my neighbor hood. IT spraying out a crazy amount of rusty water. almost like a reddish orange cloud, not tire white tire smoke.

I wasn't too surprised as there had been too many starts & stops I am sure every low spot in the pipes and mufflers had water in them.

I think the sealant mine came with was the same as ddcrank posted above.

My 78-80 trans ams have oem holes in the mufflers, however those mufflers are tipped down towards the driveshaft, so I question if they ever did any good.
Never made any leaking sounds from them though. holes are about 1/8-3/16"