I meant just what in-game code disables catch up. I found it on your other post though, all four buttons at course select. If you try using the
mame cheat tools to find addresses that change when you enter the code, it finds these 10 locations.
Address=00501AB8 Start=00 Current=01
Address=00540C32 Start=00 Current=01
Address=00540C72 Start=00 Current=01
Address=00540CB2 Start=00 Current=01
Address=00540CF2 Start=00 Current=01
Address=00540D32 Start=00 Current=01
Address=00540D72 Start=00 Current=01
Address=00540DB2 Start=00 Current=01
Address=00540DF2 Start=00 Current=01
Address=00540E32 Start=00 Current=01
I haven't really looked at what those addresses are but I'm guessing 501AB8 is perhaps relevant since it's nearer the other player memory locations (5051B4 is speed, listed in the pugsy cheat xml I directed you to in the other post). Perhaps the rest go towards driving this pixel in the corner of the screen, I don't know I didn't really look too deep. I don't know this processor and I'm not about to learn, but it feels relevant that this byte is set when you enter the code. I would set watchpoints for these and see what happens after the game starts.
Otherwise you could perhaps find the tire wear setting by starting a normal game, then flipping this bit, and then using cheats to see if there is some number somewhere that is going up or down now, probably near the player data (i.e. near that 5051B4 speed memory location).