How do u spot the difference between the 02-04 ecu and the 05-06 ecu's? i'd like to make sure when i purchase an 02-04 that its right.

Part numbers genious, jk.

i know the 02-04 is prb from hondatas website, but what is the 05-06? should i just look for PRB?

I don't know anything about the RSX's but just call your dealer and ask the guy workin in parts to look it up.

Well you said you worried that someone might be running the 05-06 ECU on the 02-04 you might buy. Well for one you can't just simply plug and play between the two ECU's, they have a different pin layout, two no one would run the 05-06 ECU because of the processor change which doesn't alow you to add K-pro. No one makes a harness to use an 05-06 ECU on an 02-04 ECU, Hondata does make a harness for the 02-04 ECU with K-Pro to be used on my year, 05-06, but because of the male/female connections you can't use the harness the other way around. I.E. For a 02-04 RSX to be powered by a 05-06 ECU. Hope this helps.

US RSX Type S with K20A2 engine (ECU part number PRB A01 through PRB A08)
2005 US RSX Type S with K20Z1 engine - ECU part number PRB-A13
2006 US RSX Type S with K20Z1 engine - ECU part number PRB-A14

^ good info. exactly what i was looking for.

+ rep