BBK sizing

[thefitter]

I’m noticing that the sizes of the BBKs offered for a E46 330i is larger than what’s offered for a E46 325i of the same year. I always thought the cars were mostly identical except for the engines. What other mechanical differences are there between the cars with regards to mounting a BBK? Assume using the same wheels.

Here is what is offered for a 2002 E46 325i:

Brembo
Front - 320mm
Rear - 294mm (exactly OE size, no gain WTF!)

WilWood
Front - 325mm (Front only kit)
Rear - 312mm (Rear add on kit)

StopTech
Front - 328mm
Rear - 328mm

Now the Brembo kit in my mind is almost no upgrade other than the calipers. Waste of money to me. Wilwood is better but still less than an inch bigger calipers. StopTech is the biggest all around but I’m not sure why the front and rear are the same.

Here is what is offered for a 2002 E46 330i:

Brembo
Front - 355mm
Rear - 345mm

WilWood
Front - 325mm (Front only kit)
Rear - 328mm (Rear add on kit)
This seems to be the same as their 4-wheel kit for the 325i.

StopTech
Front - 332mm
Rear - 328mm

Now the Brembo kit is the biggest. Wilwoods rear has changed a hair. StopTechs front has changed a hair and now the balance seems more normal.

Obviously if I buy a BBK I want it to be BIGGER. What else might I need to change other than the wheels to install the biggest BBK that’s practical?