If someone brought an RM ZR1 in we would've laughed at them and let them run it... As between the low PP restriction and tire restriction it would've been slow as molasses.
As for the "sea of NSXs"... Yep, still an issue. The NSX-R is definitely one of the quickest in the 500-550PP range. Grip is insane and it's got quite an aero advantage (a Spirit R at the same power specs as an NSX-R will get walked down long straights all day every day cos its daddy was a DJ)... Result is one very quick car. The R35 is even more of a "cheat car" IMO because of how insanely easy it is to drive and how little tuning it actually requires to be fast. Hell, we were running at Autumn Ring Mini at one point, few NSXs out and about, then an R35 got brought out and shaved a few tenths. I grabbed a bone stock '07 from the online recommended list, slapped S3s on it, and took it out. Zero effort and I'd actually beaten every NSX and my own Spirit R... And had no will to drive it after that. There was no real challenge beyond seeing how fast you could go... Car felt like instant god mode right up until you did something the computers couldn't correct for and you understeered off.
/rant