Im going to buying a new set of pistons very shortly and as i dont know anyone with either set of pistons fitted wounderd which are the best quality and offer the best strength for a 245bhp+ car. with view to gaining more power in the future.I only want to buy once ,as this is going to be costly enough.

 

Go for Wössner: http://www.woessner-kolben.de/english/indexenglish.html

They have new pistons for the cooper S with lowered compression ration 8:0 wich is highly recommended.