Bob, usually I order the PCV's when I make my "winter maintenance parts order" at one of the online parts houses. I can't rely on the local parts stores for LT5 stuff in my area.
I do them every year, but then I do between 3k to 5k miles a year. I just consider most of what I buy every winter the cost of using my car as much as I can every summer. I hate doing any maintenance during the driving season, so I try to have it all covered before I start my season. I'm like a selfish little kid once the summer starts!
Louis, I really have to say that sizing injectors for a motor, let alone our motors, is waaaaay beyond my knowledge level. I'm still putting my bet on the PCV's....
