Ya the usual, "see authorized dealer"...I have winterized the standard things motorcycles, atv's which are 4 strokes but my main concern is where if at all is there water gathered/holding on the machine. Something that will have to be drained or antifreeze put through.
I just winterized it and there is nothing to it. Dealers wanted anywhere from $150-$225. Total cost on everything was $25.00 with enough left over to DOO it again next year. Real test to see if it was done correctly is in spring. Highly suggest doing it on your own, take your time have a couple of "BUDS" and learn about the machine in the process.
or you can go to BRP-Operators guides under SeaDoo.com . A PDF will open. Choose your SeaDoo model and open the appropriate manual. Go to Storage and for the 2007 GTI SE (pages 113 thru 116) there are detailed pictures and information about how to prep the intercooler and the exhaust manifold for winter. Dlandb
Quite a bit to winterize the 4 tecs properly. You change the oil and filter, stabilized the fuel, drain water from exhaust and poor antifreeze through it, check pump grease, put the battery on trickle charge and spray the engine compartment with silicone lube. A great website is Sea-Doo.net - the official website for the Sea-Doo watercraft enthusiast I believe and it will have a link to 4 stroke winterizing. If any doubts, let the dealership do it. I found it takes about $120 dealer.