The RRC manifold from the JDM Civic Type-R (FD2) is well regarded as the best all-round intake manifold for performance K-Series engines. Replacing stock EP3 manifolds, it's easy to see gains of 15hp. Even owners of the heavy Accord K24 regard this as the only potential replacement for their stock RBB, as it's able to pack punches on the level of torque offered while far excelling at the top of the band.
It's rival choice is the RBC manifold from the Accord Euro-R, while a cheaper alternative, the RRC offers gains as high as 7-10hp at the top of the band, and 20lb/ft torque increase in the more useable mid-range - it's easy to see why this manifold is held in such high regard.
Here at H-Tune, we think numbers talk, check out Super Street's K-Series Intake Manifold Shootout for some proper facts and figures.
This manifold is a bolt on for the CL7/FN2 (K20A RBC/K20Z4) and only needs minor hose rerouting for the CL9 (K24A3) with a 65mm throttle body. For EP3/DC5 (K20A2/K20A PRC) owners the slam panel will need to be trimmed in order to physically fit this manifold into the bay, the waterport also needs to be cut which we offer as a service above, please research exactly what's required for your vehicle, there's plenty of information about the web.