I put 'intercooler' in the search block and came up with these. SOB is probably refering to page 102
Page 88 Solo rules:
F. The engine management system parameters and operation may be
modified only via the methods listed below. These allowances also
apply to forced induction cars, except that no changes to standard
boost levels, intercoolers, or boost controls are permitted. Boost
changes indirectly resulting from allowed modifications are permissible,
but directly altering or modifying the boost or turbo controls,
either mechanically or electronically, is strictly prohibited. Traction
control parameters may not be altered. Any standard OBD communications
port functionality must remain. The Check Engine Light
(CEL) or Malfunction Indicator Light (MIL) may be disabled via software.
Alternate software maps which violate these restrictions may
not be present during competition, regardless of activation.
1. Reprogrammed ECU (via hardware and/or software) may be used
in the standard housing.
2. Supplementary (“Piggyback”) ECU may be used subject to the
following restrictions:
a. Connects between the standard ECU/PCM and its wiring harness
only.
b. Must be plug-compatible with the standard ECU/PCM (no splices
page 102 where I think SOB is referencing:
3. As utilized only on engines originally equipped with forced induction,
induction charge heat exchangers (known as “intercoolers” or
“charge air coolers (CACs)”) are unrestricted in size and configuration.
Air-to-air CACs and radiators for air-to-liquid CACs must be
cooled only by the atmosphere, except for standard parts. Body
panels, fascias, or structural members may not be cut or altered
to facilitate CAC installation.