Can anyone help with the best place to purchase stainless steel exhaust risers for an AQ271 Volvo Penta. Mine were replaced in 1998 they boat is used exclusively in salt water but flushed out with fresh after every trip. But I am worried after reading a number of posts with regard to corrosion. I will look at replacing them. Should I take them of and check how badly they are corroded, if i do this should I replace the gaskets?<br />Many Thanks Nick