Hi guys.

So for the top deck and square motors all you have to do is remove a little from the underside of the top deck @ 45 deg following the curve of the motor. About 2mm is all you need. I can now go down to a 116/23 so that a ratio of around 10.09 so plenty. Not really a big issue. It also depends on what motor you are running and track layout as always.

Weight Wise I would suggest keeping the weight as close to the bottom deck as possible. There are a few countrersunk holes that can carry the HUDY style weights. 125 grams seems a lot? Mine is 1350 without the body and 1400 with it I then run 25 grams of weight.

Scooter your servo seems to be quite deep? looks like your steering arm is at around a 30deg angle. Have you tried to turn the servo mounts 180degrees so the servo ears mount towards the outside of the car? I know this will place the servo further out but this may also help with weight distrobution, I know Paul lemoix likes his cars like this. Failing that I run a 9551 and its perfect.
Also if you are having dificulty with the placement of the fan and the top deck you can re-jig your electrics. I would suggest mounting your receiver ontop of your servo (no there is no issue in weight etc) move your speedie further down and then you can flip the heatsink around 180 degrees. I did this on my xray and it worked perfectly.

As for flex in the top deck. I found that removing the front 2 and middle 2 (before the last 2 screw and after the lay shaft )counter sink screws helped on low grip ashphalt. Just make sure that the top deck doesn't rub/bind on the bulkheads at the ends.

AE velcro strap, yes please, though you could buy a TOP blue one and scratch the TOP off it lol