Sean, you're so enthusiastic, let me try to help summore. Jazzler's experience is relevant. Firstly, AB, Ingress, Sapura and Quill are 4 of several dealers of BMW Malaysia, all separate entities. Buy a BMW from any dealer, and ALL dealers in any city will honour the BSRI and warranty because the costs are recharged to BMWM.
The assembly plant makes cars in batches. Today, E90s in 1 colour, tomorrow E90s in another colour, etc. Then they make other BMW models, then even other marques. So the E90 in the colour you want is not being made all the time. When stock is low, competing SAs from competing dealers will book cars 'for their client' even if they don't have a client in hand, and you'll find that you can't get hold of one anywhere. But a few weeks ago, stock levels were high, so there were many units to choose from, with good discounts and interest rates. That was the best time to plonk for one! Now, stock may be low again, so the answers are: "sorry you'll have to wait until Jan/Feb".
Given the above info, my advice is: Scour all the dealers for the model and colour you want. If you find one, negotiate hard, but book it quickly. My final 2 cents: get the 325! You'll regret it slightly if that's the one you really want, but didn't get