I'd use split with a LIMIT and join if I were you.

Regarding your code, I don't understand your regexes and you didn't provide sample data... (or maybe you need to format more readable)

update

you are applying multiple /g regexes in a row, after substituting the 10th pipe the 11th pipe becomes the 10th, so better do it in one run.

what is !- supposed to mean???

update

took me a while to understand that you are negating a decremented counter !(--$pos) ...

If you just swapped the ternary operator you wouldn't need any negation.

Better consider checking ranges in just one single run /($count++ >9 and $count <12) ? 'pipe' : $1/

split and join is still the readable way to do it.