[s-cars] Knock Sensor...Hard to change? How much is the part?

[Cody Payne]

Gents,
	Has anyone changed their knock sensor?  Cost of the part?  Took my car over to ASW/Dave Jones today for a suspension rattling issue and he is going to change out my software too...but in doing so it appears that my knock sensor is acting up as appears to be retarding timing or reducing boost when it shouldn't be?

Thoughts?

cp