I would go with the Civic Si. It seems according to many magazines there is alot of potential for that car. When they did an intake test on the rsx-type S they got a 20 hp gain. I would imagine(correct me if i am wrong) you would get a simliar bump on the SI engine. There might be a just as much of a bottle neck in the exhaust system/headers. Plus you might be able to use Jdm civic type r stuff on it also. I am not sure about that on because i think the type R engine is K20a and the Si engine is K20a2( i think). In other words they are similiar but not the same. In other words I would take the SI

ronin