i have a 14' aluminum with a 1982 2 stroke 7.5 evirude, i did add a removable deck and floors totalling about an extra 50 or so lbs. with me only the motor does ok but with one more it plows . i would like to get a 9.9 or a 15 h.p (max for motor) 2 stroke or is a 4 stroke better? my question is there any diff. from the older motors to the newer one, i mean newer as in 1990 thru 2000 or so. ie: power , performance wieght, i would think a 9.9 would plain my boat with the added wgt. i know the 15 will ,