im actually tempted to put my d15z1 head on my d16z6 block since the vtec on the vx pulls harder than any sohc vtec car I have been in. I have a d15z1(vx motor) in my 4dr civic and when vtec engauges the car pulls ALOT. I love how noticable the speed increase is. But on every d16z6 I have driven you can only hear a high pitch whine but dont feel any difference in pull.