For racing, neither one but to answer the question: The Civic Si.There is very little room to increase the Si 197hp factory K20 engine without upgrading the internals and other stuff. The thing I don't like about this engine is the 139 lb-ft of torque. Other models such as the Mazdaspeed 3, WRX & Evo have a lot more HP and double the torque because they have factory turbos. The 2009 Accord V6 is one of those engines with cylinder deactivation. Honda made it to run on 3 cylinders OR 4 cylinders when cruising. Probably not a good idea to mod this engine.