Question for fellow 6'3 170 (40L) sized guys - looking for slim-fit non-baggy snowboard jacket. Tired a Sidewinder Med - length is fine but still baggy. Large was huge. Is an Alpha better for my preference? (wont layer much other than merino or power-stretch fleece if needed). thanks! Also - for California - do I need SV or LT?

DONT LISTEN TO THESE FOOLS. I'm 6'3 and 165 and I wear a medium. It fits two layers (base + softshell) underneath and if need be also a light syn insulation layer. You want the jacket to be as SMALL as possible without feeling restricted. If the jacket is too large, the pit zips will be a pain to open and close.

I am 6'3" 180lbs and size L fits perfectly even with 2 layers underneath (a shirt and a fleece jacket).

If a Med. Sidewinder fit length-wise then that is probably what i would try in this jacket. It is an athletic fit jacket. For california? I believe that an LT would be more than enough. LT in the Arc naming scheme stands for Lightweight, whereas the SV stands for severe weather. An LT is generally a 3-layer gore-tex shell as opposed to the pro shell, although there are some pro shell LT jackets. I use an Alpha SL (super lightweight) pullover which is the pac-lite shell that has taken pretty much any abuse i can dish out.

Just an FYI - I do have the Rab Latok Alpine jacket and in a size medium it is very comparable to an Arcteryx size medium.

Look at Rab, they're a Euro manufacturer and their garmets tend to run slim.

The Alpha jackets wil definitely be less baggy than the Sidewinder jackets but I'm 5'10" 175 lbs and I wear a medium comfortably - at 6'3" you are going to need at least a large to get enough length; I'm thinking that you are still going to find this baggy. The Arcteryx shells tend to be about the least baggy of the main manufacturers in the US marketplace, but I am of the impression that many European manufacturers design for a taller, thinner body type like yours. I have no personal experience with any of their shells but you might check out offerings from Mammut or Norrona and see if they might work for you too. As far as SV vs. LT it really depends on how hard you will be on the jacket. I have an older LT (non-Pro Shell) and I think it's more than adequate for most people. It really is a great shell- I'd recommend trying it just to see if it could work for you.