Some guys do but its definetly ideal to have at least an A2A intercooler. You will really see the benefits of meth with already lowered IATs. At 20psi your making a lot of heat with the blower and with a good A2A and a dual nozzle meth setup your IATs shouldnt be much higher then ambient if they arent at or below that.
I woulndt run any blower @20psi with no intercooler! just doesnt make sense powerwise, as stated 20psi creates a lot of heat, and spinning a blower to 20psi without an intercooler is a waste imo.
Get youeself a good A2A inercooler and enjoy your boost!
If it's anything from a Fox-body to an 04 Cobra just ditch the oem bumper support for a Chromoly piece and the added weight difference becomes zero by installing an A-A Intercooler... Ask me how I know? And OP do both Meth AND an Intercooler