I think you may be right in that your car could be more planted (depending on setting) with all those Al parts due to the added weight.
i just tried to spread the weight evenly so that its proportional to weight of the motor in the back in effect there are more metal in front than the back wich also strengthen the front for some misshaps... I love it! so far my car been performing great specially when i got 16t pinion on it. its really nice on the track!! even my fellow racers like the car saying its stable... il post some pics of the car so that you guys can see what i did on it....