Have located some new old stock neoprene mufflers (that apparently are no longer being produced.) They are new, an appropriately sized for my 427 FE Fords at 300HP. Advertised as being much better ("80%") than standard mufflers (think the original tin cans on there now from 1966). Also advertised as less backpressure. Supposedly impervious to acids, fumes, liquids, and heat in the exhaust. Nothing not to like, right? Anyone have any experience or comment about these Salisbury neoprene mufflers? Especially interested in how they may compare to fiberglass mufflers as to cost, durability and performance. Thanks for any comment you may have.