Well weight is weight. And when you are talking about a car that has 7.5 Hp and you can eject 400+ pounds of weight that’s like 2" 200 Lb passengers don’t matter what your driving. Eject 400 pounds and your gonna notice a difference. But I agree with you on your Batterys are new so you don’t wanna throw them out. Spend your $ on other things, just don’t waste it on a Motor. IMO it’s not going to make any real difference in speed or range. You will be pissed if you spend $800+ on a motor and your car go’s no faster. Only thing a 7.5 Hp motor is gonna do is allow you to spin it faster. Higher rpms stock motors don’t like to go over 6k for any time. How about some nice wheels and tires or a stereo, or you could always look for a Used E6 that needs batteries and throw your FLA batterys in that and re- sell it I’m sure you can re-coupe your $ and then get a Lithium kit. Trust me you will love it