You can get a 30 without items, assuming, of course, you can get ahold of five wishes somehow without an item. Otherwise you're back to 25. And there are definitely feats that require higher than a 25. I couldn't name them, but I remember seeing prereqs of Dex 29 and Con 29 in some places.
A while back, maybe in Sage Advice in Dragon, someone asked if stat-enhancing items could be used to qualify for feats, and the sage said yes, with the same "lose the item" caveat. He also said that feats in the ELH were designed with that in mind, and if you're playing without many stat-boosting items, you should probably drop some of the prereqs for feats.
A while back, maybe in Sage Advice in Dragon, someone asked if stat-enhancing items could be used to qualify for feats, and the sage said yes, with the same "lose the item" caveat. He also said that feats in the ELH were designed with that in mind, and if you're playing without many stat-boosting items, you should probably drop some of the prereqs for feats.