Just a thought. Has it been tested with limiter differences? It's been a while, but I always tried to use above 95% as the car's handling seem to deteriorate below that, basically washing each other out. This may not be the case anymore however, idk.
Cars generally have a better power curve if you don't reduce too much. They will feel "better" or more "natural". But accel out of corners and down straights is still vastly improved by flattening the curve out. So, racers know this and add extra parts. Some will even take a small hit on PP if it means they can get higher TQ or HP out of it. Depending on track and car, it can have a huge difference.
I can show up on nights where HP and KG are not locked down, and race against people I normally smoke, and on every corner exit, get left in the dust. I can work hard to chase someone back down, taking a better line etc., and then they blow right past me again. If next race I figure out what is going on, and do the same to the car, I am neck and neck with those cars on the straights....