I have a 97 Honda Civic with an H22 Swap. I was running it all motor at first, ported head and dynoed at 218 with a Hondata. I decided to turbocharge it using a thicker head gasket to drop compression (T3/T4 Turbo, small intercooler and with a 38 mm Tial Wastegate) and got it tuned with Hondata S200. Watching the dyno screen, when VTEC kicks in at 5200 rpm, horsepower/torque would drop by 20 hp then it would pick up again. On the otherhand, when VTEC was set at 6000 rpm, it would only drop 8 hp, then picks up again. Ignition and AFR are both where it should be. VTEC function was verified as well as oil pressure. No CEL at all.
I'm faced with two issues right now.
1. Horsepower drops when VTEC kicks. When VTEC is set at 5200 or 5500, hp drops by 20 and when it's set at 6000 rpm, it only drops 8. Boost holds when VTEC hits but power drops.
2. Max boost is 6 lbs when I have a 10 lb. spring. Boost does not hold, would lose 1 lb after 7000 rpm.

I did not have that VTEC problem when it was all motor. Only thing done to the motor was to replace the head gasket.

 

try lowering your vtec point to 1-200 rpms befor turbo spools. or you may need to lean your fuel for those rpms that power drops. got to remeber the ecu adds fuel for vtec and
plus your adding boost what was your a/f when you lost power?