K20A = Motor for DC5 ITR and EP3 CTR in some markets, but not all. This would be the "Integra Type R" that looks like an RSX and the "Civic Type R" that looks like the US Civic Si of the '02-'05 type. About 220 DIN HP in 2004.

K20A2 = Motor for DC5 RSX Type S, Australian Integra Type R, and Civic Type R in some markets. About 200 DIN HP in 2004.

K20A3 = Motor in US RSX base model, Canadian RSX Premium model, and US Civic Si of the '02-'05 era. About 160 DIN HP in 2004.

EP3 = Chassis code for USDM Civic Si of '02-'05 era.

Other chassis codes you'll see a lot of:

BB = Honda Prelude

DC2 = Integra of '93-'01 era.

EG = Civic hatch of '92-95 era.

On and on....