OK, maybe I should be posting this in the turbo section,
but I talked to Ben at JWT this morning. JWT has been using HL series cams for quite a while in project cars but for some reason didn't promote them until not too long ago.
From what I understood the HL cams are designed to give more air flow without moving the power band further up the RPM range.( the way the S4 moves the power band further up than the S3 )
The question of which is better S4 or the S4HL seems to depend on your setup/modifications. The S4HL cams can give more power than the S4 and within the same RPM range IF your engine can take advantage of the increased air flow.( more boost,bigger turbo, etc.)
Not trying to start an (NA) DE vs VE discussion since I believe the VE is the better flowing head but I would think that, with the right mods, the S4HL cams should make the DE more competitive with VE.
Anyway, the general impression I came away with is the HL cams are the ones to use. Can anyone with more technical knowledge point out some drawbacks?