Yeah, but are you sure you're REALLY giving 100%???
You'd be amazed what you can do when you just force your body past the pain - I'm still learning this - I'm sure I'll always be learning this. Try doing 20 - 30 reps with a weight you are sure you can only do 12 with. THAT'S intensity. If necessary, do breathing reps, where you take a few breaths between lifts/reps.
Spatts, it kicks my ass pretty well, i'm also natty, were i juicing right now, i'd probably up the volume, but when you are doing 90% of your 1rm til failure, you will be sore.