Exchange sacrifice in Exchange Gruenfeld

Isn't there a variation of the Exchange Gruenfeld where White passively sacrifices the exchange by allowing Black to play ...Bxa1.  Somebody did this to me today though I don't think in the precise variation I'm thinking of, but rather in a similarly thematic way.

I've just started playing the Gruenfeld again and need to be reminded.  Thanks in advance

Yes I seem to recall that one.  In my game White's d5 push attacked my Nc6.   After ...Bxa1 Qxa1, I stupidly played ...Na5 when White had Bh6 threatening mate and winning back the exchange after the ugly ...f6

attacking the knight on c6 with the d5 pawn? something like this? black can easily get in such trouble if he castle to early which is

why playing 7..c5 and delaying castling is better

You do take on a1. Then white gets a ferocious attack. You're lucky to survive - but if you do, you often get a fantastic endgame (although sometimes even endgames are ok for white thanks to activity). 

This is the kind of position (after you grab on a1) where each tempo counts, there are zillions of options for both sides and of course it's hot - the best player, the player who knows the ideas better, the player who's sharper on his game - will prevail (or it can be a draw of course). 

It's important to understand also, that you get sharp positions, where even if you manage to secure a winning advantage - often you need to take care of counterplay, as surprises are very likely to happen. 

i dont play the grunfield myself as black but i know this sequence with Qa5 has been played by kasparov and almost the entire chess elite. thats what i would look into myself

Two things:

1. Did you look at my game?  Just curious because it's pretty much identical
2. 17.Ne6+! instead of 17.Nxe2

ops i moved to quick. somehow i took on f8 with king instead of queen and i didnt look at the board just blindly inputting notation. well i didnt look at your game but as white that spesific position i have gotten many times in my club. black moves are natural i guess. in my 1.d4 book by kornev on the grunfeldchapter the first thing the author does is to tell you 7...0-0 by black is bad and tell you what to do

So in the meantime I looked at your line and actually after 17.Ne6+ I think a position can arise where White has a Queen for Black's Rook and Knight, so it's a variation Black might want to at least consider.  As for 7...0-0 being bad, yes another player at the same tournament said so, but frankly I don't understand the move order nuance: I have to castly sometime, right?