Once you install the suction pipe you'll get airflow cut. This happened with me and that's with the stock turbo, at around 4k RPM
I timed it so that after I got the suction pipe, I had Scott's hi flow and injectors installed the next week, then off to tune on the Saturday.
You'd also have to baby the car till its tuned (this is if you upgrade the injectors and what not)...I got sick of staying off boost pretty quick!
Depending on the size of injector you're upgrading to, you won't be able to drive it unless you've got a basic map put in via a piggyback. My car was at Scotts for a few days getting all the mods put in and when it was ready to go Cihan came to install emanage and loaded a basic map into it so I can drive it...