I want to put a turbo or two in my blazer 2020

If you're asking a question this basic, the answer is to pay a shop to do it. You will not be doing any part of this installation yourself whatsoever. You will need to enlist the support of those well-versed in welding custom manifolds, those able to tune the computer, and generally a project manager that knows what's involved in doing the work. This means Google around for a performance shop that does things like this.

Rumor is Lingenfelter is working on a supercharger kit to produce 450HP like the Colorado kit, assuming you have a V6. That will be infinitely easier, when available.

Agreed with the above. Wait until the Lingenfelter kit or be ready and willing to dump a boatload of money into the truck and be willing to have the truck be a throw away. It'll be a guinea pig.

I'll be interested to see how your 9T50 trans holds up. Keep us informed.

Not a snowballs chance in hell the 9T50 holds up.