WHAT DOES JDM HONDA REPLACEMENT ENGINE MEAN?

Can n e one explain to me what sort of acquire in hp i must b having? Also so i'v looked at getting a mugen air filter an box to but there v expensive, dose n e just one no if its really worth receiving one particular an what attain I might get from it. Thanx AshtonHaving said that, the demand for people K20 variants has also built them more expens