My factory 2.2 can handle (and flow) 500hp with nothing more than a bigger snail and fuel support... and over 800hp fully built (as Stephane* has demonstrated). That's a design that goes back to the mid 80's.
While DSMs are incredible machines for their time... Don't forget the pioneers.
*A rookie "garage style" NHRA race team with a Chrysler TIII powered Dodge Charger GLHS that took 3rd place in it's class against multi-million dollar competitors.
http://nhraimport.com/2007/drivers/S_Beauregard.html