Here it is the stats:

Regular Season:
4232 for 6531, 64.8%, 50,128 yds, 366 TD, 181 INT, 95.2 QBR, 7.68 Y/A

Playoffs:
435 for 692, 62.9%, 5,164 yds, 28 TD, 19 INT, 87.6 QBR, 7.46 Y/A

Since 2003 Peyton has played 15 of his 18 playoff games.

His regular season and Playoff stats from 2003 to now?

Regular Season
2483 for 3714, 66.9%, 29,510 yds, 228 TD, 6.1 TD%, 81 INTs, 2.2 INT%, 102.2 QBR, 7.95 Y/A

Playoffs
385 for 587, 65.6%, 4,606 yds, 27 TDs, 4.6 TD%, 17 INTs, 2.9 INT%, 92.7 QBR, 7.85 Y/A

Not a huge difference, but the TD and INT numbers are a bit telling IMO.

The most important playoff stat is playoff stat is he is 9-9