You're talking about 3.5, so you might want to consider the Grim-N-Gritty alternate combat rules for something like this. It achieves the basic goal of low HP numbers that you seem to be after here: everyone has a 25-point "life bar," and there is no way to extend it. Instead, you have to use other means to become tougher as level rises, such as dodge bonuses and DR (including a universal form of DR which they call "Soak"). Tactical movement and defense, especially concerning things like cover, become much more important, and monsters become terrifying.

You're talking about 3.5, so you might want to consider the Grim-N-Gritty alternate combat rules for something like this. 

It achieves the basic goal of low HP numbers that you seem to be after here: everyone has a 25-point "life bar," and there is no way to extend it. Instead, you have to use other means to become tougher as level rises, such as dodge bonuses and DR (including a universal form of DR which they call "Soak"). Tactical movement and defense, especially concerning things like cover, become much more important, and monsters become terrifying.