I've raced on Vittoria EVO tubulars with stan's sealant in them.
We're talking less than 2 ounces here.
I can't feel any difference between riding with and without the sealant, and it does fix/stop small leaks.
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You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.