I use the stock Cat orange in the secondary with that helix so I would put that in. To get your rpms up with the heavy snow doesn't have anything to do with the helix really, it's your clutch weights. You can use various brands of adjustable weights, I only use Cutler turbo mags. With your mods you would use the 80-90g set and I would guess around 82-83 grams at 4-6000 ft, more weight with lower elevation as what you make for boost is limited to what air the turbo can compress....and it is easier for it to do that at lower elevations. Heavier snow would drop a couple grams to maintain your rpm.
An Evo reflash will make more power at elevation because Evo can manipulate timing, usually it needs a couple grams more weight than a BD 2.0. FYI every weight acts differently because of the arm profile. The Cutler TM weights run about 5g lighter for the same rpm, ie. 85g stock is like 80g in a Cutler TM.
I use the 38/44 or 38/46 helixes from 177hp to 325hp. It's just the weight in the primary that changes.