In a small bowl combine salt, pepper, garlic powder, and onion powder. Season the chicken on both sides with the seasoning. Lightly grease the grates of an outdoor grill.
Heat the grill to medium-high heat. Add the chicken and cook turning at least once for about 10 minutes or until the chicken is fully cooked (the internal temperature has reached 165 degrees F.). Remove from the grill and let rest for 5 minutes.
Turn the heat to low and split the sub rolls and place cut-side down onto the grill until lightly toasted.
Slice the chicken.
In a medium bowl combine romaine lettuce with Caesar salad dressing.
To make the subs place 3 strips of bacon onto each sub roll, top with some romaine lettuce, 2 tomato slices, some grilled chicken strips, and parmesan cheese.