Ive thought about this swap often.

In my case, the financially smartest thing to do would be to find the cheapest crossfire thats still nice($10000 or less). But this is the easy part. How much will that swap cost? $40000...$50000? By the time its done id have a $50000 crossfire.

I think id be better off buying an SL55 AMG and own a MB with similar power.