Can the Spesh brain be added to a stumpy comp as an upgrade ? As it only comes on the Expert model and above !

The shock is the same length, but I don't think the rear end of my Elite frame has the necessary fixing points for the 'Brain' part of the shock.

I know for sure that the Expert has an extra 'cable' mount at the top of the non-drive side with a little plastic bit that secures the hose between the Brain & the shock, that the Elite doesn't have.

So, at a guess you'd need a new rear end to fix the Brain in place.

I tried the Brain and while it seemed to do what it should, I don't miss it on the Elite. It made a subtle clunk through the rear end everytime it activated that felt like I'd just hit the rear rim into a root. I'm sure you'd get used to it, but I found it quite annoying….

I've got a brain on an '07 Sjer, I know its a slightly older system that the current brain fade, but on a SJer, I'd much prefer a propedal adjustment on the shock than a brain. I leave it turned off most of the time to let it respond a bit quicker and to get a bit more traction (brain on runs less sag) when climbing
My brain leaked its pressurising nitrogen once (brain completely off) and the rear wheel had so much more traction than running the brain on its most off setting

On an epic I can see it being pretty awesome, but on a SJer I don't (personally) see it as an 'upgrade'

I've got a Brain shock on my Epic and a pro-pedal one on my Enduro – both are very effective.

The Stumpjumper falls between them however I'd be more inclined to go with a good pro-pedal shock than a Brain if it were my bike, as the Brain seems to best suit the racey nature of the Epic.

Theoretically it can, they do usually (although not always) have the mount on the swing arm, but you'd have to get hold of a shock from somewhere, which would be the difficult part!

Talk to Spesh if you're interested, although frankly I suspect it'd cost too much to be worthwhile.

"I suspect it'd cost too much to be worthwhile"
When I sent my shock/brain for service, the shop I bought it from (Bikescene-Guisborough) said I should insure it for about £450. So it'd probably cost you more than a Fox RP23?

Well they don't really have a retail price, IIRC Spesh tend to 'assign' it a value of c£300, but that's more than the price difference between the non-Brain/Brain models of bike used to be!