So Parts go Street, Sport, and Race but how about a 4th graded part called Super.
These parts have a Even greater performance boost than Race parts but also have a Downside.
Lets say Super Cams have a even higher redline but having the car at that redline for to long will damage the engine, Super Turbos could have more lag , Super fuel management could have you uses a lot more fuel than projected. Super weight reduction (example Acid dipped camaro) could leave your car extremely light weight but more flimsy and fragile that any contact will hurt the car. Super air filter will not work when drafting other cars because of dirty air. Super (time attack) tires will last for a very short while enough to do 2 good laps and fall off dramatically.
This, on top of my old suggestion being More adjustable parts and upgrade "level" name change
1 Like
Please not. Sounds like NFS feature. 
3 Likes
Better than not modifying the current FM3 old upgrade system
They could call them Stock/Street/Sport/Race/Drag. Drag could have high engine power and torque but also as a downside like you said a lot of fuel consumption and more wear if you hit the rev limiter. Would be cool to build 1000hp+ cars for the drag strip or just for fun to race around the track (or map in FH5).