I recently bought an Arcteryx Fission SV. The one feature that I really wish it had is a stowable hood. I have a few other jackets (Rab Neutrino Plus and OR Chaos) that have insulated hoods that roll up and are secured in place with a strip of material (an inch or two wide) that runs from the inside of the neck, loops over the rolled hood, and is fixed to a velcro tab on the outside back of the collar. I've been thinking about trying to alter the Fission to mimic the rollup feature of Neutrino and Chaos. I think I can get GoreTex material similar to the jacket but worry that I might mess up an otherwise nice jacket. Any advice? Am I crazy to consider this?

its a $650 jacket, why would you void its warrant for a feature it used have and was useless on a heavily insulated shell? if you want a roll away hood from Arc'teryx get a Sentry or a Fission AR jacket. the insulated collar makes it hard to roll away the hood and makes the collar super stiff and in the way.

1. Got it on a pretty good sale - $450. Still pricey but a little less crazy.
2. Tried the AR but, a) didn't like the tighter fit, b) didn't like the shorter length, and c) wanted the extra insulation in the SV, and d) wanted an insulated hood. Also looked at the Sentry a while back and while I don't recall all the reasons that I rejected it, I do remember that I like the SV a lot more.
3. Not terribly concerned about voiding the warranty. I'm pretty easy on clothing. Have purchased quite a few quality jackets during the past 30+ years and never needed to use a manufacturer's warranty.
4. Finally, a roll-away hood may be useless, and annoying, to some but I find it a nice "option". For those who don't want it stowed, just let it hang loose.