Upgrade from 22mm master cylinder....really necessary? Your experience and thoughts please

In a position where I need to.replace my 22mm brake master cylinder in my mk1 1 gti with audi front calipers and 16v rear calipers. Is it worth going to a larger master cylinder or better to stick with OEM replacement along with the existing 16v 9" servo?

Any experiences of this?

I'm running a 1.8T engine hence the modified have setup.

I put the Audi hangers with std callipers and discs on rear if 2.0l 8v. Was a decent upgrade with std master cylinder but can't say if it would be adequate on 20v