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It's beneficial to lower your vtec engagement point to help alleviate the infamous pre-vtec dip. My tuner started at 5000rpm and went down in 100 rpm increments. When we hit 4400 we were no longer seeing positive results so it was set at 4500. This gives me a 4700 rpm powerband
It appears the more boost you have down low, the sooner you want the Vtec to engage. We started out with a couple hundred rpm lowering and over the last two years as the pulley size got smaller the Vtec responded lower and lower. Mine with a BAR of boost total is currently transitioning to Vtec at 4000 rpm. It does increase the midrange torque nicely.
Similar to JohnZ, this gives me a very large powerband.
Notice the Vtec torque dip is almost non existant. The dyno was at 13.8lbs boost total & Vtec engaged at 4000rpm.
This older dyno is my baseline with stock Vtec activation point superimposed over 7 lbs boost with the Vtec set at 4800rpm. Notice the large +/- 1000rpm torque dip.
Just remember boys and girls, you must have an aftermarket EMS to do this.
Dropping the Vtec with just a VAFC will cause all sorts of problems and you will loose power.
It does increase the midrange torque nicely. 
but not w/ the same setup...