I drove a 325 and a 330 the same day when I was looking to buy. I noticed the difference right away, and the decision was simple - 330.
I raced a guy in a 325ci this summer. Hehe, I came up to the light after he did, so I knew he had a 325, he probably didn't know I was in a 330. We were both stopped at the traffic light, I wasn't looking for a race. But out of the side of my eye, I saw him get all excited, he started playing with his shifter and talking real fast and loud to his girl in the car. I figured he wanted to race, but I let him make the call.
He dropped the clutch and made it clear that it was a race. I gave him about a car length and jumped on it in SLIPtronic manual. Within 50 yards I was a full car length ahead, he gave up and backed off. And the convertible weighs about 400 lbs. more than the coupe....