bump

 

How high is your engine oil fuel dilution? How often are you changing your engine oil?

 

The people that are seeing the most gains in the midrange with a lowered VTEC engagement point are using a test pipe and an exhaust of the same diameter. Even with a stock (non-damaged!) header, people are still seeing great midrange gains like the ones ans2k was speaking about.

 

I just had my NA 2005 with vafc-2 tuned at T1 by Tony Palo. He is one of if not the best honda tuner in DFW! I have greddy duals, invidia tp, plm header, and fipk intake. About 2 weeks prior to getting the tune but after I installed the vafc my vtec started delaying engagement (wouldn't kick in until 6300 or so rpm), i don't know why. After the tune its back to normal and I can feel a huge difference in the midrange. He lowered my vtec to 4700! On the dyno my gains to the wheel went from 209.3 to 211.2 whereas, he stated, most all the other na s2k's he has seen gained only about 5 hp with similar bolt ons...

 

Maybe 5hp at peak. In the midrange, though, you should see huge gains with a lowered VTEC engagement. Even down to 3500 is an okay RPM for engagement. Personally, I'd do around 4k, just for a bit higher oil pressure. It would make me more comfortable with it.

 

It seems for your setup, the stock header is restricting your flow. Could you post a before and after plot(s)?