If you feel that the car is down on power and you can handle more, i'd look at the motor and cells.
Even a speed controller with a different drive frequency can help, in stock i'd suggest the lowest setting you can get away with unless wheelspin is an issue (Shouldnt be unless its a cold, low grip track).
Obviously, also the weight of the car/electrics can affect how quick the car will spool up. When I raced a tc3 I milled out the centre strengthening brace of the chassis, this allowed the cells to sit a few more mm towards the middle of the car, giving the car a better C of G, and also shaved a bit of weight off. It didnt seem to affect the strength of the chassis either.
If I remember rightly, a few of the AE team guys in that era also did this modification.
If you're only racing stock and you dont tap the boards (doesnt sound like you do with your results!) Switch over to the composite driveshafts if you want to shave some weight.
IRS also make lightweight shafts for the gearbox pinion gear assemblys if you want to save a bit more weight over the stock items, might be tricky to find now though.
I'd probably keep the original carbon propshaft in too, over an alloy one (if you can find one) if you really want to keep the weight down.
Even plastic shocks off the RTR kits might save a few grams too over the alloy ones, but may not be as durable.
Use alloy hex's on the end of the stub axles though, or it can be too easy to bind up the hex to the wheel/axle when the wheel nut is done up.
As for a screw set, swap out the kit version for titanium, stronger than alloy but probably the same weight or less. I made the mistake of putting alloy screws on the gearbox covers, bad move!
I used the team version of the car since its release in about 2000 for quite a few seasons racing, then moved onto the Tamiya ta05 as it was a lot more durable for me, maybe I just board tapped it too much or I didnt have it setup quite right lol, but it won a fair few club races and won an A final once or twice.
Weight is the killer in stock, the quicker you can get the car to spool up and keep its speed through the corners, the better your laptimes will be if you're not help up in back markers.
Hope that helps