For a street car... I'd be going the 25/30 but actually probably looking at the 3540 or a touch smaller.
On the street, for a very tractable car, you want and need response.
Also, in the comparison of a 25DET VS 25/30DET, think about the fact, they may both make 400KW, but the 25/30 will do it roughly 1000RPM earlier... Meaning there is way more torque being put down, which is what makes you go fast.