exedy twin disk and carbon d-shaft
 

if anyone here has used it.

What do you want? Feedback? Some actual questions or concerns would be helpful. That way, we know what type of answer you are expecting.

I have gt35r on my car and i thought it was little laggy. to improve the turbo lag I thought about reducing drive train weight. obviously it will help but wasn't sure how much it will help. Is it worth the $? clutch is something i need it now but drive shaft is extra.

Turbo lag deals w/ the sizing of your turbo...not associated w/ the weight of the drivetrain.

Switching to a carbon fiber driveshaft will do nothing to help your lag. It will reduce the weight (a bit) and reduce driveline shock, but will not really help your lag. But the reality of this is while you're reducing weight w/ the carbon fiber driveshaft, you're ADDING weight by switching to the twin plate clutch.