1. Engine oil.
Selenia engine oil is what is recommended, Alfa Romeo Brera Engine oil
however I used Castrol 5w40, as any 5w40 is fine I am sure. Just make sure you increase the service interval on your 3.2. I am doing mine every 5,000 miles or every year to decrease the chance of chain stretch.
Do you mean oil filter? if so its a generic paper one, £6 off ebay or any of the Alfa parts website. All the same. Or do you mean air filter? If so, two options. Option one is a replacement one that will use the original air filter housing. Here you are looking at an OEM one for £20 or an after market replacement like a K&N or Pipercross for a little more. Option two is a complete after market air filter, not using the existing housing. Again K&N offer these. I have just bought an ITG one and currently waiting on a silicon reducer to fit it. Some thing like this http://www.ebay.co.uk/itm/ITG-Maxoge...item25747bf183
however the general consensus is induction kits are a waste of money.
3. Sports cat or decat
Cannot offer advice here as I havent done this. I did have the centre silencer removed and made a subtle difference to the engine noise and note.
I am currently looking into this. Autodelta (Autodelta Shop
) offer a remap that increases bhp by 14 as well as increasing rev range. However it is £475. A few other companies offer remaps for cheaper, around £200-£300 but not sure what the benefits are apart from the generic "more power, better mpg, etc" And where? all over.
Angel tuning offer one that will give you 10bhp more, but its £340. http://www.angeltuning.co.uk/engine-...ar-tuning.aspx
Quantum tuning offer a 14bhp increase, no price though... http://www.quantumtuning.co.uk/car-r...eo&Range=Brera