Hi I had a mikuni My30 M4 heater kit installed , was going to do my self , but on reading info was clear for insurance best done by proffesional , it was cheaper than webasto or eberspacher equivalent , but got rave reviews , infact the marine electrician that fitted it has now taken on an agency for them himself as he was so impressed with the heater and mikuni company .
He installed the heater in starboard side of stern space on bulkhead , there was allready air duct towars this space from factory fitted air vents . he ran ducting down starboard side , although holes had been precut by manufacterer he still had to mod /cut some of them due to cabling runs , it runs down centre of boat under cockpit , then under starboard berth , under instrument panel behind seat , then below and behind chart table , into locker under strbd seat (vent fitted here ) and then through main bulkhead into locker under seat strbd side ,forecabin , with vent .
I fitted the vents to both aft cabins at later date , dead easy , tee'd into pipe etc , all i needed extra to kit was an 1m length of 80mm pipe , everything else included .
I too am very impressed with the heater which does a great job , even with aft vents open will still reach forecabin .It has been well tested especially last 3 months in scotland ! ,
plan to run smaller pipe and vent to heads next winter .
Led lights bought from ebay as advised elsewhere in this forum , just the cheap ones which work fine , dont have a smart charger so dont get great spikes that will blow them (so far !)