RE: Getting started in pylon?
The Thunder Tiger Pro 40 is the only legal engine for the 424 class.
Typically the races furnish the propeller (APC 9" x 6") and the fuel (typically 15% nitro).
The 424 class Q-500 racer is a lot of fun without spending a lot of money.
The Great Planes Viper is the most popular of the models.