Someone said that in a thread I posted. That only applies if you are using a boost controller to get to 8 psi.
So if you want 16 psi with a boost controller, you need AT LEAST an 8 psi actuator. That doesn't mean you can't use anything from 8-16.

I see, okay, so should I get a wastegate that has a Cracking pressure at 3 PSI; opens fully at 7 PSI
or should i get a wastegate that has a Cracking pressure is at 7 PSI; opens fully at 10 PSI?

I want to maintain 7-8 PSI and have good spool, less lag.

Cracking pressure? That's dependent on whether you're testing it with a hand pump or with the car actually in boost. If you want 7-8 pounds, get a 6 pound spring with a boost controller. It's what I'm using minus the boost controller. Boost controller helps spool/lag.

That was some reading. I like the diy adjustable wg idea. You really just need a lower rated wastegate around 4-5psi if you can nail that on that spot. Attach your boost controller assuming you can figure that out. Loosen it a good bit so it doesn't affect the wastegate at all.

Then go drive the car, make sure it's hitting the said 4-5psi just fine. Pull over somewhere, turn boost controller clockwise to adjust your psi. Turn it slightly though and repeat your test run. Do this pulling over and boost controller adjustment until you have your desired boost then leave it the hell alone. :)