I have used both on a turbo car and they actually compare well.
-The VEC has an annoying drawback in that it does not handle throttle tip in well on a turbo car. Supercharged cars don't seem to have the problem as much. There is some hidden software in the VEC that you may be able to get Roe to unlock for you to improve it, but it's not available to the novice user.
-The Split second does not have that problem, and it has more load sites, so you can get a much better tune with the split second box than the VEC - absolutely.
-Both keep your OBD II, but the VEC hides things like bad injectors or coils from the PCM so it's harder to debug a problem like this, the VEC connector is really lousy and it's not waterproof and is mounted under the hood. I have had VEC II's that are non-working, taken them apart and removed the dirt and moisture and they have worked again.
-The split second can be mounted in car and does not suffer from this.
-The VEC has a nice extra feature, the PWM output that can be used for water injection, NOS, or another injector which is a nice feature.
It's really a toss up in my opinion, both do a decent job.
-Dave.
