2005-2006 RSX ECU's cant be used with K-Pro, the use of and adapter harness and a 2002-2004 ECU must be used...

The 2006 RSX-S ECU is a PBR-A14

You can use this ECU with a Re-flash tho, but if extensive parts are upgraded a K-pro upgrade would be a much better idea as the reflash'es are for basic I/E and there are no other reflashes available from HONDATA the the basic one...

Here is a short list as to other ECU's in other cars

IDENTIFYING HONDA/ACURA ECU'S