I was running a 3.7 and Matt had a 3.9 The 3.7 is better matched for corners and 3.9 probably better for top end. It's a drag race from climbing bank to entry at Nascar 3. Hold your line low off bank and no one with 3.7 can get around. From there back to oval it's a skating contest as there is no binder left between all the smooth pebbles called macadam and there are few passing spots unless someone bobbles a little.
3.9 actually was best in 510 also.
I'm trying to raise enough $$ to buy up stock in my company so both our 240's, trailers, tow vehicles, and spares are available. That includes 8 new rains on Libres, and 18 Hoosiers, 8 with one heat cycle, mounted on Panasports.