Just use the internal wastegate that will come with the kit.. it should be good for 1 bar at tops (14.7psi) probably even more depending on the internal wastegate and how stable it is. Only do your external wastegate when you feel that the internal wastegate can't handle things too well anymore

 

I was using an IHI RHF5 ballbearing turbo on my D16Y8, and used the internal wastegate on that for months (at 1 bar) before changing to an external wastegate, because I wanted to boost 18psi daily, and my internal wastegate couldn't take it very well..

 

Do you know the trim on the apex sohc turbo? How does it compare to drag and revhard?