My lightnings are standard, not Stainless (Wish I'd had the extra $$). Made 50HP on a moderately moddified 454 with stock heads and low compression.
I sure like the looks of the Tri-Y's, and want those at repalcement time.
I have been told that the Bassets will make a bit more power, being actual differeing length tuned headers, but I do not know for certain, and, if I got 50 HP (200 RPM) from my Lightnings, maybe 55 from the Bassets? Nothing I'd be able to tell anyhow.
Good luck to you. I don't think either will dissapoint you.