In our first Test & Tune with the K20Z3-based Honda Civic Si, we managed to bump up the power production with an overall 12.6 peak whp gained, with sections of the powerband showing increases as much as 19.1 whp. These power increases were realized with basic bolt-on products and an engine-refreshing upgrade to synthetic oil. For this round of parts, we decided to turn our attention to the area in and around the cylinder head to see if a few more aggressive bolt-ons could add power to our naturally-aspirated coupe.

Text by Arnold Eugenio // Photos by Jeren Walker, Vinh Nguyen and Richard Fong // Wrenching by Jeren Walker


The Parts

test-tune-civic-si-103-002First in line for installation on this round was the Vibrant Performance 4-2-1 Stainless-Steel Race Header with the cat-delete option. A properly designed exhaust header can effectively harness the scavenging effects of exhaust pulses, reducing backpressure into the system and allowing the engine to run more efficiently. On race-applications, deleting the catalytic converter can further increase the exhaust gas flow and reduce the amount of back pressure seen by the system.



If removing the catalytic converter is not an option, Vibrant Performance also offers a similarly-designed stainless-steel race header that includes a high-flow catalytic converter. With specially-designed exhaust runners feeding into a metal-core catalytic converter, the T304 polished stainless-steel header terminates in a 2 1/2-inch outlet flange that will bolt up to most aftermarket exhaust systems.




The last two parts tested work in conjunction with each other – the Drag Cartel Drop In Cams and the Hondata FlashPro reflash. The Drag Cartel DICs are iVTEC-compatible camshafts that have a more aggressive lobe profile than stock for moderate power increases without needing to upgrade the rest of the valvetrain. With the camshafts in place, the factory fuel and ignition timing maps should be modified to take advantage of the increased air flow. For that purpose, we chose Hondata’s FlashPro hardware and software combination. Installing the FlashPro unit allows the end-user to reflash the factory ECU with pre-configured fuel and ignition maps and offers the ability to fine tune the map tables for a specific application. FlashPro software also offers a datalogging capability to ensure the new tables are performing as expected in the vehicle.

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