Spark Plugs in 2002 TB

What type of spark are factory installed on a 2002 TB? Are they iridium, platinum, or some combination? I am changing mine at 100,000 miles and would like to get at least 50,000 miles out of the ones I replace them with. I'm sure iridium are the best but they're also the most expensive. Are there any disadvantages to using the Bosch Platinum 4+ or even 2+ instead? I can get these at a much better price. Thanks.

Plats, the most recent replacement is 41-103 iriduiums set at .50. Stay with AC!

Got the AC iridiums for $7 each. Thanks and I hope that's the last set I buy.