From what I understand RR setup is different, chassis has to be tighter or it will be very lose on the corners, and you’ll be fighting that the whole time.
Sprint set up you have to free up the kart to get it to glide through the corners
I don’t understand about steel bumper? Unless you’re talking about the rear bumper, I’m not a big fan of metal bumpers on the rear, I like plastic bumpers better, and they do have brackets for those to fit your Margay Kart.
You wanna tighten up the bumper for RR, and loosen it up for Sprint racing.
I don’t know what the specs are for your chassis for front track or for rear track, you may wanna ask the guys you run with at the track, but it is also different from RR to Sprint. My 2 cents.