Originally Posted by BGTV8

I use these rotors on an 1100kg 540 hp modified production sports car and they work just fine. Rotors are cold-fired before use and I get a full season out of each set which is less than half the price of AP Racing rotors.

If you are concerned at the aesthetics then learn to live with it, or go back to OEM rotors.

The slots are engineered to provide the minimum space for gases released from the pads during hi-speed stops
This is old, outdated info. Only crap, REALLY crap pads need slots

In terms of rotor ring design, DBA makes a number of rings from one source casting and these rings are then machined for 332 OD all the way up to 356mm OD.

These rings need to accommodate centre bores from 190 to 200mm and most of these sizes have a common rotor mount PCD of 215.9mm and need to accomodate both 10 and 12 bolt mountings.

The inner face ID varies between 225mm to 231 mm

A common base ring reduces the cost for a number of fitments.
100% correct; DBA did this to limit their internal SKUs to increase profit. By any chance, did you or the OP weigh them before installing them?

I can tell you that one design objective was to provide the minimum material removal to provide sufficient slot-space to accommodate gas released during repeated high speed stops when rotor temps are likely to reach 900 DegC.

As for a comment about zinc-plating to avoid rust in an earlier thread .... pulleeeez .... zinc coating has absolutely no role in this place

It has all been designed ... if you don't care for the aesthetic, choose another product, but these rotors "work".