Is that exact reason why the Z-tune is a 2.8?
Bubba - the MA70 Supra turbo A was a 3L in group A
Also not entirely applicable to RB's
but related to the displacement Debate.
Ford once build a 302cube (4.9L) V8 for NASCAR to run agaisnt the 350-360 cube motors that the other manufactures were using (icl Ford at the the time)
the 302 was so much faster than the bigger motors on the Ovals and the Road circuits simply because they revved a shit load more.
They accelerated faster because they revved quicker, they had more top speed because thye could easily pull another 1500-2000rpm without falling apart etc
In the End NASCAR changed the rules so that the engines had to be between 340 and 365 cubes.
Same goes with the 2.6 vs 3.0 debate, so while the 3.0 might get a bigger turbo on song sooner which makes a fair difference in Turbo cars. but the 2.6 will sure rev a lot quicker than the 3.0.
Also has less strain on bearings with the lighter crank, piston speeds are less etc, so being able to use more revs in the 2.6 doesnt really hurt them reliability wise over the a lower revving RB30.