Strength gains
Lets look at a few things. Are you allowing enough recovery time between your workouts? Are you varying your chest routine at all? Are you eating enough nutritious food to supplement your strength workouts?
Suggestions:
Try taking a full week to 10 days off of working your chest only. I know that when I do this, I am so much stronger when I come back to the workout.
If you have been using the PS chest tape for some time, it may be that your body has become too comfortable with that routine. To remedy this, you can try the following before returning to this tape as is:
1) You can take the exercises on this tape and change the order of the chest exercises.
2) You can find your own exercises(or use the ones on the PS tape but in a different order)and work chest on a day all by itself. If doing this option, be sure to warm up thoroughly and then lift as heavy as you can using a weight that you can safely handle with good form.
3) You can also do the same exact above options for triceps too, since stronger triceps are a contributing link to a stronger chest.
4) When doing pushups, try working negatives. For example, you can try this: Three non consecutive days per week, do 2 sets of 10 toe pushups BUT BUT BUT start up at the top of the movement and take 15 seconds to lower yourself down to the bottom of the pushup. If you have to collapse before you start up the next one, then go ahead BUT IMMEDIATELY get right up and in the ready position for the next one.
5) You can try substituting dumbells for all the barbell exercises to provide variety. Eventually when you go back to using the barbell, you might be surprised to find out that you can actually use a heavier weight.
Be sure to eat enough food to supplement your workouts and also eat a wide variety of nutritious foods. If you do not eat enough food or good food, you will never get stronger.
If you are lifting very heavy, it helps to put a little extra protein into your diet to aid in tissue repair.
If you are exceptionally sore after a particular workout, rest the next day and perhaps even the following day after that. Muscles receive their benefits while you rest. This is when they repair and refuel themselves.
Good luck with everything and I hope this helps!