Yes if you mod the engine the best course to take would be to up the quality of the oil use to cope with the extra stress, temps and genaral hard use of modded engines.

If the engine is heavily modded and used hard then you combine better quality with a slightly thicker oil, usually one grade, so from a 5w-40 for a stock car to a 10w-50 to a heavily modded car.

Cheers

Simon.