We did a Cobb ATR custom tune for a fairly stock ’06 Civic Si. While COBB has since discontinued NA products, this was a great test. Read the article from Modified here:
Most of the gains came from the VTEC switchover, which Honda leave late on purpose for the “VTEC KICKED IN YES!!” feeling. But a bit of cam timing and leaning the engine out a small amount made a few more HP.