Correct plugs for the ECO 150HP 2005 V6

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Hi, I have recently bought a Johnson 150HP V6 2 stroke and have changed the plugs. I have replaced them with like for like but am not sure that these are the correct plugs as they are marked for a 50HP engine. The plugs used are NGK 2622 BUHW. I found some old plugs on board also NGK BPZ8HS10. Can you please shed any light on which are the correct plugs to use and if there is a preferred gap setting or plug orientation (ie:earthing post towards the injectors?). I am in Australia so it may be an Aussie built motor. Thanks,