oppinions??

[brucer]

what are you guys oppinions on such things as power boost valves,chips and uprated clucthes(as in black diamond ones)

so far i havnt heard much good bout products like these.an how there a waste of money. obviously theres gotta be some good in them.

what you lot think?
would be goin on my nova gte so would i be gaining anything from fitting these?