Volumiser
That's the only one I'd hands down reccomend, with an adjustable RAM cap second if you were using a HALO.
All the others:
Triggers
Equaliser
LP barbs
Bolt
WAS eye
Switch
Hard detents
Rams
etc etc
..... are all really for the sake of it, they do have
some effect but I'd not say any are real real important.
Of course - if you anything like me you'll get all on them anyway regardless of whether they actually do anything