LT1GMC

Having my HHRSS a week, it was time to look underneath at the bottom side. Well made, 3" exhaust till rear section, then 2.5 the rest of the way, beefy front axles, bigger than a Caddy I worked on yesterday, pretty tidy all in all. However, I've noticed a buzzing/jingly noise sometimes when going thru the gears. I found the exhaust pipe has a thin aluminum heat shield running pretty much the whole length from the rear axle to the engine. It is only attached at the ends, with a long section that is flimsy and vibrates with the flip of the finger. It is 1/4" away from the sides of the tunnel, so I squirted RTV silicone in the clearance gap 3 places each side to dampen the tinny metal from vibrating. Success!

hvrod

I hope you used the high temperature (Red) Silicone sealant for it...

LT1GMC

No, you don't need it there, its on the back side of the heat shield, a good 3 inches away from the exhaust pipe, and downstream from the cat by a foot.