To re-iterate what GSO said, do not bend your rear axles. Scout axles are bent already straight out of the box and tuning the rear is almost a must (if you can). I have seen people test scout cars on my track and with a only a k-house groove in the rears axles, some have gained several tenths (not hundredths, but tenths) by tuning the rear axles. Bending rear axles will only compound the tuning problem. You could consider these:
https://www.derbydad4hire.com/BSA-Speed-Axles-A-PBSA.htm
They are essentially BSA axles (or as close as you can get to BSA axles) that are straight and deburred. You could use BSA axles, deburr them and ultimately get the same performance, these just save you a lot of work (and headaches); but I do understand they are not BSA axles from the box.
If you must use BSA axles, buy 50 or 100 of them (
https://www.derbydad4hire.com/Set-Of-10-BSA-Replacement-Axles-A-004.htm) at 10 for $1. To select good scout axles, chuck the axle up in a drill. You'll can which axles are bent and which ones are straight with the drill at low to medium speed. For the front axle, do not use the Derby Worx axle press to bend your front axle. Instead, give it to your closest competitor. Cut a bend groove in your front axle and use a hammer and screwdriver to bend it. I just the video of John bending a front axle with those simple tools.
Slots make your tuning problem even worse than with BSA axles alone. You might consider drilling the rear with a jig (if you have access to one) at the stock locations and then recreate the slot below the drilled hole. It's a grey area to me and I do consider it within the rules. The canted rear helps the rear wheels migrate away from the car body towards the axle head where friction is less. It also gets most of the wheel off of the track.
And while we are at it, clean wheels are fast wheels. Do not get graphite on your wheels. You might consider getting something like this to prep your wheel surface / edges and clean your wheels:
https://www.derbydad4hire.com/Pro-Wheel-Tread-Cleaner-T-PWTC.htm