My buddy has a new 05 s2k, and currently it has about 500 miles on it. He notices that under heavy acceleration when he shifts gears it seems as though the clutch is slipping. Is this the clutch, or could it be the diff? I need some input on this topic.

 

Put the car in 6th and drive it up a steep ass hill.

 

Well I live in Florida, and there are no hills. What will that tell me if the clutch is slipping?

 

Most likely he's feeling the clutch slave cylinder delay valve

Here's more info
https://www.s2ki.com/forums/index.php?showtopic=275175

 

Its the slave cylinder (delay valve)......remove it.