Definitely. The gears on some Gr.3 cars are just a bit too long and there's no way that they'll ever come near the redline in 6th (or 7th) with the current BoP.
For the 911 what I was finding was not as much a actual top speed problem because the car would not reach red line in high gear was the car did not possess enough torque to overcome the aero drag and weight and was an acceleration problem of not being capable to at least maintain a reasonable acceleration rate as compared to the competitor cars on the long straights.
If the car was still able to match the basic acceleration rate of the other cars that would have at least allowed the 911 to remain in contact while in a slipstream but on this track with such long straights in stock BoP trim even being and remaining in the slipstream was difficult at best, almost not possible.
Most tracks I find the 911 strengths will offset the weaknesses(of course the last bop adjustment hurt the car to a degree) but this is where I think the main problem exist.
Regardless depending on which circuit and which car when you use a single BoP class standard for all tracks, certain tracks will favor certain cars, just the nature of the beast.
Fine when a single BoP standard is used across a series that utilizes the drivers having to use the same car across multiple circuits with different attributes as where one car may be strong on track A, another it may be track B while it is track C for even another make.
The whole thing is that the variety of the circuits encountered will balance the makes out over a series of tracks that are different.
Daily races do not possess that variety and each day a class runs on one circuit only.
For that scenario to be balanced as far as BoP across the board at one circuit among all the cars within a racing class the BoP standards need to be set independently for each car for each individual circuit. Otherwise there will remain tracks that certain cars cannot be used and expected to be competitive with class.
This to me is not a proper application of what BoP is for. And yes having races that are based strictly on only racing one track and individual results of that race is all that matters does require all cars to be EQUAL in BoP to all cars in the class.
Actually in GR3 personally the Corvette would probably be my choice as a car I would use overall on most circuits while we only have one Standard that covers all circuits.