They don't have an intercooler because they're running straight methanol/alcohol for fuel rather than gas. An alcohol race motor is an entirely different beast than even a highly tuned gas motor, even if it looks similar from the outside. You can get away with things that just wouldn't fly on a gas motor (like removing the intercooler completely). This is a very specialized motor for a specialized application.
If you're looking for inspiration to tune your "street" motor look to guys that have achieved big power on race gas like alltrac101 (Pat Chinshue) or tjdouble07.