I have Enchanting at 100
Maxed out the 5 ranks of enchanter perks
Activated the Insightful and Corpeus Enchanter perks
Activated dual enchantment perk (although it's not needed)
Using a Grand Soul Gem (with Grand Soul); the most I can get a piece of armor up to is 15% Fortify Destruction. I thought using the steps above would get you to 25%.....am I missing something (maybe updates have changed the ability to do this?)

I do not know how high it can go, but try using an enchanting potion with it to make the enchantment stronger.

The strongest enchanting potion one can make gives a 32% bonus. This will make your 15% into 19-20%.

Hmm that's very curious. I have always been able to enchant w/ 25% Fortify once you have all the perks you described.

Either your game is bugged or you don't have what you say you have.

100 Enchanting + Enchanter 5 + Insightful Enchanter = Fortify 25%

Have you actually clicked the enchantment and not just scrolled over it?

nm

I'm 100% positive that I have all the perks and that enchanting is at 100. Another oddity is that it doesn't appear that I am able to enchant a ring with Fortify Destruction on a ring that I have. I'm starting to think my game is glitched....

If your picking the enchanted effect that also gives you magika regen, you'll find that it is lower. You must use the enchanted effect that only has fortify destruction to get the 25%.

^This

15% Fortify and 10% Magicka Regen. I have all the perks you have and get 25% fortify.

Oh, smart thinking. That also explains why he can't put it on a ring.

yes, that makes sense now that I think about it....I was getting greedy and trying to dual enchant with magika regen. I'll try with only Fortify Destruction and see where I get.

Fortify Enchanting potion

I have maxed my alchemy, enchanting.
without using the exploit:
I can make a fortify enchanting potion 33%
i can enchant 4 pieces to have 29% fortify alchemy, necklace, ring, hood, 1 more forgot what it is.
i can make resist X-elementanl (i forgot the exact number, its roughly 45-54%)

Go to Radiant Raiment in Solitude and you'll find most of the enchantments there. They sell a lot of enchanted jewlery and apparel.

http://www.youtube.com/watch?v=pbDD-P7_Xo0