Thanks for your comments. We had an autocross scheduled for july 26 on the Big Island that I was thinking of going to since Oahu autocross Aloha Stadium location is closed until further notice likely October due to the lot being filled with rental cars that have no other place to sit during tourism shutdown. However hurricane Douglas just passed through leaving rain, wind and waves on all the island and forced the cancellation of the Big Island event. Maybe next month. If I go I would fly over and co drive a car that is already there, it's not ideal, a very short small paved go kart track next to the Hilo Drag strip. If it rains it could all get underwater quickly as it is at sea level in the tsunami inundation zone.
OK, it is possible that the A052 or RE71R rubber is softer and allows for a little more grip and maybe a faster run but as always that depends on optimizing everything else that goes with driving well. That your Goodyear feels controllable and suits your driving style is important. Getting to know the tire and how to make the best of it may require a little testing and trial and error. Every course can be different enough to require small changes. It looks like your courses flow well enough and have turns and slaloms that would benefit from the cleanest tight driving line you can manage at grip limit so that should always be the goal and offer you the best time. You cannot control anything else but what you do with your car and setup.
I put video cams on both right and left sides to see how I am doing along the course for steering and cone placement. I want to be touching or within 3 inches of cones at the apex locations or with slaloms. Everytime I am one foot from the cone I may be giving up 0.1 second depending on the speed (about 35-40 mph). No run is going to be perfect but I will see tendencies of being close or further on the right or left front turning or even the trailing rear wheels if I hit anything. Though you are trying to backside cones it is common to miss the mark and end up being pretty far from doing what is planned. Every small detail adds up and leads to your total run time, you gain some then you loose some. If you have anything large to correct then start there first and whittle down the problems to minor stuff what will vary from run to run. I have never found a run to be perfect even when I have FTD for an event. I just made less errors than others that day.
Overdriving can be a factor so if that is something you contend with then find ways to stay calm and within yourself. Dial back just a bit but stay at traction limit which is the goal or catch that oversteer tendency the moment before you have it interfere, it's a very fine point. I usually set my rear bar to get just a tiny bit of oversteer, not too much because I want to be able to push it and allow a little four wheel slide that is controllable.
When you drive are you using VDC off or in R mode. With VDC in R mode do you detect enough interference/braking that it becomes a hidderance?
On your mentioned variables-
More weight is definitely a negative since it takes energy to change acceleration or to brake with heavier wheels/tires.
Sidewalls more stiff- there is less flex so would lower tire pressure be of any help? Getting overworked may be related to your slip angles and driving approach which could be more aggressive- something to look at and adjust a little. Consideration for future tire that allows you to drive with your natural style with less adjustment.
Oversteer- lots of reasons for this but bottomline is your tires are not holding enough grip for what you are asking them to do. Earlier and smoother input in steering with less weight transfer will allow more rear tire grip and better control. Your slaloms don't look too tightly spaced, uneven or offset so you will have to find your sweetspot for finding the cleanest shortest line and hold speed well if you have the traction to do so. I usually look at slalom with prioritizing them if I have more than one on a given course. The longest more widely spaced slalom is the closest thing to a straight that I will see so it is of the highest priority on course. Entry to the long slalom allows me to carry more speed through the whole slalom until I get to the last two cones and accelerate out if I am not coming up to the tight turn. Finding the fastest entry speed that is not too agressive is key as no braking during the slalom is key (kills the flow and my pace, too busy to manage steering while brake and throttle are not constant).
Rear bar settings- I have a 19mm (thin) whiteline rear adjustable bar with three holes on each side. I have both sides set for the middle hole after trying one on stiffest and not liking it. It was a little too stiff for tight turning on my courses. I also like the bar settings to work with both R compound tires I use and with Extreme Summer street tires I use so that I don't have to adjust much. I use R mode almost always and have tried VDC off with poor results for the grip the tires were allowing at the time I tested it over the course of several seasons. It's not that I can't drive with VDC off but that if any small error is made that cannot be corrected in time then the whole run is blown. I have no practice runs and have 4 tries during competition. In Runoffs I have 3 runs per course that is flipped at midday. Since my courses are short my tires often are not up to best temperature for grip until the last two runs if any. I run about 120-130 degrees in front and only 110 degrees most of the time, sometimes 5 to 10 degrees more on a hot day.
Are you checking tire temperatures during the event to adjust pressures. What kind of pressures are your getting? Something to play with a little.
The other question I have is this- if you are allowed to do fun runs at the end of the day, how do your times compare with during the event? Do they overlap- do your times drop and if so by how much? Obviously as we get more experienced we are able to learn from the course and adjust better for a faster run time. If we are all given ten runs then the margin between each competitor may be very very small. That your times are better during fun runs may indicate that you can find a faster way on course without the advantage of optimal tire temps. Yes, the course can be improved by more rubber laid down on course in the right places or in my case it gets worse with more gravel at the start launch or in tight turns where gravel builds up.
Key learning for me is I always do fun runs in street tires and I find that within 2 or 3 runs I can nearly match my event time on race tires due to learning the course better and applying adjustments, normally I think of difference in Race and Street tires being about 1 second for 30 sec course. I will see less than 0.5 sec difference with my fun run time and event time so there is always much room for improvement for me. And of course the conditions for driving are different during and after the event with respect to the driver's focus, concentration, calmness, hydration, etc. I am very busy and rushed organizing the event and barely make it to the grid in time for the start. I am last in my heat to allow the most prep time and barely make it.