I am purchasing a 2015 290BR with twin 350MAG MPIs with Seacore. It is a saltwater boat with 265 hours. I had the selling broker service the outdrives, replace all fluids, and pull and inspect the risers. He tells me the risers a fine, for now. He says the manifolds on closed cooling systems don't usually need to be replaced. He will replace the risers for $4000 at my expense if I want. Does $4000 seem high just for risers. He sent the attached photo of the riser internals.