I've been playing around with pilum stats for a few days now, just to see if I could find a something that felt right to me. After 15 or 20 minor alterations I've ended up with this...
In weapon_data.csv
Damage: 450
Projectile Speed: 250 (hurricane MIRV main missile speed)
Launch Speed: 50
Flight time: 25
Hit Points: 120
In type_1_lrm.proj
turnAcc: 15
turnRate: 30
acc: 70
dec:60
Every other stat remains the same (granted that changed most of them)
These pilums are faster, less accurate, slightly lower dps, don't clump up so horribly, and work great for long range support ships. It gives them a presence on the field right off the bat.
They usually only get 1 or 2 chances to hit an enemy ship instead of following them around like ducklings, and can no longer be effectively used at assault ranges (unless you aim really really well).
They are a credible threat to any size ship, but can be easily dodged by a frigate, can be evaded by most destroyers, and fast cruisers can sometimes scooch out of the way.
I find these stats for pilums highly appealing, both for my ships and the ones I fight against.