You can buy different inserts gold and purple silver is standard i swapped from silver to gold not much of a difference to be honest u just unscrew a few alan key bolts on the top the unit comes apart then u just swap the inserts .In my opinion if u go buying a new valve dont get a cheap one as your car will not hold boost properly hks might sound a bit wierd at first but it grows on u after a while and they will not affect your turbo boosting at high load where as a cheaper unit like forge or bailey just feel like there at braking point at high boost i think turbosmart are meant to be loud and reliable but pricey.
