My take is this .... that car never came with these manifolds ,period , then a set was brought for a crazy price on eBay .They where put on the car too make it look original ,then the car was advertised for sale for a high price . I wish the seller well in his sale but those looking to buy such a car know this ones history.
If they are reproduced the only loser is the buyer who originally paid the high price for the manifolds. As a rare piece they have value BUT don't add to this cars value unfortunately. imo