. Both heat shields (one above the cat, and one above the muffler) technically are all part of the exhaust system, so I'll assume you were referring to the rear one above the muffler. It's the easiest one to get to AND the first one to usually go on these 2nd gen Vibes. My son lost his rear heat shield some three years ago or so as the rivets/bolts rotted out. Not a real big deal here in the Midwest. If we were Texas or Florida I'd probably would have replaced it. He's been fine since then.