Kind of weird question....
I build an Locost 2 years ago and now i'm changing V6 engine with 20VT one.
In order to use as short turbo piping as possible and due to FMIC fitting issues(actually it will be RMIC because the cooler will sit behind me) it will be great if i can point the throttle in different angle. I plan to cut the yellow marked section(picture below), reweld it and move it away from the head.......
But......the pressured air makes 90 degree turn when pass the throttle and into the plenum. I'm sure that they make some calculation when designing turbo intake system.
Will change in this angle make any difference in air quantity for 5th cylinder for example?
It will be even better for me if i turn TB 90 degree to point straight into the plenum. But will i mess the air flow somehow?

The plenum would have been CFD'd by Fiat likely for cylinder balance/optimisation, what you plan to do will change this but by how much is unknown territory. I would advise fitting a lambda sensor per cylinder to triming per cylinder fuelling assuming your management system can cater for this.