PLenum/TB--Good deal on ebay
 

Hey Guys! Will this combo work on our 986S?

Porsche 997 3.8S 911 Carrera GT3 Competition 82mm Plenum kit & Throttle Body

The general consensus is you do not gain any benefit of going bigger than a 74MM throttle body from a 996/997. It's been mention that it can actually decrease performance with the 986. Unless you have a 3.8L engine in your Boxster stick with the 997 throttle body and 997 plenum. It should give you more power without changing the airbox first.