all the 4rth gens I owned v6 or v8 had a slight ticking/taping sound that seamed to be comming from the air box/ intake and especially if you had a aftermarket air intake. I beleive it's called valve taping. I don't recall ever hearing it inside the car , you could only hear it when you got close to the front of the car. Anyhow from my understanding slight valve taping is not a big deal. One way to fix it is getting a louder exhaust.
