The 06 gulfstream w/ twin yamaha 150's that I bought one month ago had 71 hours on the twins. The boat had the winter service last year and then it was placed for sale this spring. I am assuming that the oil was changed, etc. when the boat was serviced for the new season/sale. I already put 30 hours on it and the display is telling me the 100 hour service is due. Is this something that needs to get done immediately, or can i wait for the end of the season to do it? Also, what is the usual cost to perform this service ? Thanks for the advice.