The exhaust actually has factory weep holes for water to drain.The bottoms and seems like the left side get the most abuse, so you may still have extra holes.
The CA 160 has both an inner and outer chain front chain covers ( the rear one is in that pic too) covers A & B,
04 COVER B, DRIVE CHAIN 11655-225-000
04 COVER A, DRIVE CHAIN 11661-225-000
found at
Western Hills Honda
I'll look to see if I've got one- and post later.