Ballast is mainly for FF cars or cars with less weight over the drive tires. RWD with 50/50, 45/55, or more weight over the drive tires almost never need the ballast - the exception being crazy amounts of horsepower like the McLaren F1. It weighs nothing and has nearly 900hp, which seems like a good combination but, without SRF or TCS, it will spin on launch up to 5th gear. It's a great track car but can't get traction on the strip.
Anyway, the XJ13 is a nice car for the 700hp it has, and it runs pretty quick with a good tune. The 330 P4 Ferrari is faster and the Mark IV is slower, so its a good middle-ground and looks the nicest of the bunch.