What is a good clutch to use on a stock gsr but wanting to boost it in 6 months or so....or around 400whp?

Wow... Here u have to go all the way...! I personally think that a 6 puck recing clutch from F1, ACT or Exedy would to the trick

the more hardcore you get with the clutch, the more of a bitc* it is to drive. the exedy stage 2 isn't super bad to let out and will hold that power provided you aren't slipping it hard on slicks.