I understand the theory a little bit but I have never personally noticed in any way the difference between no stacks, stock 2"? stack or some tall ones that were maybe 5"
Not a bean...
That said, we're massively compromised on intake length anyway and the exhaust primaries aren't ideal if you look into some of the maths, so in the scheme of things, tuning the intakes on an otherwise **** setup is futile.
If you have custom manifolds, ITBs, perfect port work, proper tuned exhaust (4-2-1?) and access to fancy software or dyno time then there are no doubt plenty of gains to be had.