Tire service cost due to excessively high top speed is usually the biggest factor in high service costs. It’s very easy to miss because the game doesn’t warn you about it and the service cost number is hidden away. Try setting your speed limiter to different numbers and see how the service costs change.
I don’t think peak power at redline is worth binning by itself, but probably in combination with other factors. There’s nothing inherently wrong or undrivable about it - you can find dyno plots of real world cars that also make peak power at redline.
Correct me if I’m wrong, but in my mind, the main problems are
- The car will not accelerate as fast as its horsepower figure suggests, because that power is not accessible throughout the rev range
- When shifting at redline, the power will jump from a high figure to a lower figure
7000 is already a pretty reasonable redline for this market segment. You should also consider lowering the cam profile and playing around with exhaust sizing to try pushing the torque curve towards lower RPMs.