Level 20 is the best version but the explanation on how to get it on UESP is cofusing. If it has something to do with your previouse level, before you level up wouldn't downloading and playing the DLC after attaining level 20 ensure the best armour?

You are talking about Crimson Scar Armor, and yes installing the DLC after you have reached level 20 is how you are guaranteed the best version, but if you are on a PC you can download mods to autolevel the armor, or eliminate the levelling entirely by using the CS.

Crimson Scar, is that it's official name? Just to make sure we're talking about the same armour, it's from the Mehrunes Razor DLC and I play on the 360.

I got my DLC's confused, but the rule still applies about activating the DLC after level 20 to guarantee the best version.

Thanks.