I think he means that bigger wheels and tires will help the grip levels on the heavier car, helping to balance some of the advantage the 325 might otherwise have.

In other words, given 189 stock hp in the 325 and 225 in the 330, on 15" wheels and 7" rims, the 325 can use its power better -- the 330 will struggle to take advantage of its extra power and torque (theoretically anyway).

On 17 or 18" inch, 8.5" wide rims, the 330 has more grip within which to use its power advantage.

I'm with you on lightness though. I just bought a Lotus Exige, and it's amazing what a 2000 lb car feels like even compared to my race car at 2560. The Exige feels lighter and more nimble than our SMs.

This will be interesting. The 325 is essentially the SM of ITR. Light.