Percodan has 325 mg of aspirin in it or so.

Hydrocodone itself is a narcotic analgesic unrelated to acetaminophen.
Some commercial medications containing hydrocodone also contain
acetaminophen (e.g., Vicodin).  Others contain aspirin instead.

Your physician presumably has taken any potential problems into account,
if you have only one physician handling all your medication; ask her for
guidelines.  If you have medications from several physicians, make sure
each of them knows about the others.

Anyway, for information purposes (not medical advice):

The toxicity of aspirin and acetaminophen are not cumulative, first of
all, so that's not a problem.

Acetaminophen is a problem beyond 3 grams or so a day or 90 mg/kg, or 7
grams in one dose--depending on your weight and any problems you may
have in clearing it (kidney or liver disease, etc.).  The symptoms of
acetaminophen poisoning are deferred, and the consequences can be grave
(destruction of the liver), but there is a specific treatment for
toxicity, if it is recognized in time.

Aspirin has a much higher toxic dose, around 500 mg/kg for lethal doses,
although toxicity may be observed at 150 mg/kg and above.  The same
caveats exist for problems in clearance.  Aspirin poisoning is difficult
to treat and may be insidious in onset, and has a significant mortality
rate.  Ringing of the ears is a common symptom even at nontoxic doses.