Okay, you know when vtec kicks in it flows more oil through the the head right, well depending on the size of the turbo you might not get the required amount of oil to supply the turbo while in vtec, also it is easier to tune non-vtec because there is not a power band where you have to add more fuel and so forth when the vtec kicks in. Do ya see what I'm saying? Also you could have 10 to 1 compression and still boost, It is just alot more difficult to tune because you have alot less margin of era. The less compression you have (not to low) the more of an area you have to tune. I hope this helps.

Rep me up.