With all these very high caster numbers, I hope you guys are talking about power steering. The original questioner didn't mention power or manual, but you sure don't want +5 deg caster with manual steering.
I set mine at 0 to +1 for manual. Above (and at) +1, you can really feel the difference and steering gets hard.
Bob
AAR 4-speed 3.91, Tor-Red;
70 440 6 pack Roadrunner 4-speed 3.54, Plum Crazy;
68 Formula S conv 383 4-speed 3.23, Electric Blue;
69 Barracuda conv Slant 6 OD4 2.94, 71 B5 Blue;
78 Lil' Red Truck, Red;
70 Challenger S/E. 505 6 pack, Passon 5-speed, 3.55, B7 Blue
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