Ok the lag problem is probably if you have too much power in the engine, like if you are using an N/A Tune with a Turbo, or you are using a really high % turbo. Some turbos just don't like some engines, this is a big problem with the F1 engines...
Try using Nissan Z Concept tires, they are the biggest rims in the game.
Try using Nissan Z Concept tires, they are the biggest rims in the game.