I've found fSmithingConditionFactor, fSmthingArmorMax, fSmthingWaponMax ...
I've played around with these a fair bit. You might have noticed that steel smithing at anything below smithing level 22, with the steel smithing perk, will not allow you to upgrade steel to anything better than fine, which you can do without the perk. I'd call that a bug. I was trying to fix it.
fSmithingConditionFactor - default value 0.5825
This will modify the "spread" and for the skill values that determine the next upgrade level. Setting it to 0.8 will bring the minimum required smithing level with the required perk down to 20 but the level required for the first legendary also drops, down to 70 IIRC. Mixed with giving steel smithing a skill requirement of 20, this works well, but it's a bit overpowered. And you'll hit legendary without the required perk at 127 instead of 168.
Going the other way extends the required smithing level for the different improvement levels considerably, but makes the problem outlined above even worse. Set to 0.28, you will not be able to upgrade a steel weapon to superior until smithing level 30, with the perk. There appears to be no offset to reduce the base alone.
fSmthingWeaponMax
This will modify the damage increase an upgrade gives to weapons. There's some problems if you want to reduce it to tone things down a bit as setting it below about 6 will actually stop you from being able to do some upgrades without the relevant perk, depending on level. Increase it and your legendary upgrades become truely legendary.
fSmthingArmorMax
I assume it's the equivalent for armor as above for weapons, but I've never tested it.
I changed PerkSkillBoosts for tempering to 0.5 instead of 0.01 ... I put on my smithing gear and it changed a ton ...
http://www.gamesas.com/topic/1345143-scaling-from-skill-value/page__view__findpost__p__20294119
Multiplying your smithing skill 26 times tends to do that.