what purpose do these serve?
#4
yep i believe thats what it is. on ebay for 50 bucks. says improves power and performance.
#7
What you have pictured is a wastegate. It's used for turbochargers to allow excess exhaust gases to escape in order to protect the turbo.
If you don't have a turbo, this is useless and you will see no gains whatsoever.
If you don't have a turbo, this is useless and you will see no gains whatsoever.