Power Drop

[Spec]

Tip to all tuners: When modifying your car, don't max out the power all at
once. If you plan to keep your car for a while and it reaches the 500 mile
mark, plan on losing about 7-11 Hp with NA cars and about 20 Hp with
turbo cars, so leave room to retune...

 

[Blaze Kinser]

That'll happen no matter what, it's just the effect of the car being driven in. If you install a level 3 turbo and run the car for 500 miles, it'll have the same HP as a car that's had the turbo installed after the 500 miles has been added on. At least that's been my experience... from what I understand after a certain point all the cars' HP figures will level out and that's that.