There's nothing wrong with Bosch plugs, or NGK for that matter, provided they are what the specifications call for. Don't try to get fancy, or fall for the marketing hype, just stay with what the book calls for and you'll be fine, not only is there no need for platinum, uranium, plutonium, cubic zirconia, or whatever kind of plugs, and their expense, they can actually run worse, and cause damage, as you've found out.