What do you mean it does not have the larger runners? It is the PI or Non-PI, there is no in between intakes.
The stock one has a lot of excess plastic on around the intake's runners but, Doman makes a skelontanized version w/less plastic and a extra temp. sensor for aftermarket temps gauges.
I guess the dorman replacement in 99-01 did not have the larger runners therefore not producing more power. Which judging from what I know about the PI intake the dorman "PI" that i have definitively does not have the larger runners.
Basically it just has PI ports and an aluminum crossover