I found a bug for with rev counter in the Nissan Fairlady 240ZH (HS30). I have the car swapped with the Roadster Shop Rampage engine in it.
The Rampage engine has, according to the car settings, its redline at 7,725 rpm (with a custom ECU, but no other changes). However, in the 240ZH, the rev counter only indicates approximately 5,900 rpm when you reach the redline of the Rampage engine. At these revs, the rev counter needle is pointed up and to the right at roughly a 45° angle. I cross-checked this information with the Fairlady 432, which has a very similar instrument cluster, but which rev counter goes up to 10,000 rpm (whereas the 240ZH's rev counter only goes up to 8,000 rpm). When revving the 432 to 7,725 rpm, its needle is exactly at the same 45° angle. This supports my theory that, by accident, PD "copied over" the rev counter from the Fairlady 432 to the Fairlady 240 and forgot to adjust the needle movement to the now different rev counter disc scale. As a result, in the 240ZH the needle "behaves" as if it were on a 10,000 rpm disc, but it is in fact on an 8,000 rpm disc. Therefore, the needle will indicate lower revs than the engine actually is doing.
I can only test this for the swapped car as I do not have a non-swapped 240ZH and it isn't available for purchase right now, but I assume this is a general bug with the car and will appear with the original engine, too. If someone has an unswapped 240ZH and wants to test this, please report back with your findings here. Thank you!