1) I got mine from LMF Vauxhall - ebay store and came in the original alfa box - metal mani with plastic flaps - very helpful guys but I probably paid over the odds (see 2).
2) I did the above before I new about CDTi surgery who will send you a deflapped exchange unit at a MUCH lower cost - there are some threads on this and CDTi surgery have a facebook page.
3) You can change the plastic mani for the ally one but you have to make sure the ally mani is a CF4 mani which would originally have been fitted with swirls - this is because there is an actuator arm bolted to the bottom of the mani. Once deflapped, the actuator should be bolted to the bottom of the mani and plugged in but NOT connected to anything because there won't be a master flap for it to control! this is purely to leave the switch connected to the ECU to make it think it is controlling a flap and stops any MCSF.
I have the original alfa mani from my 06 car sitting in the garage and, having sold the GT, I have no need for it. It has simply been removed, replaced with the new and I kept it to get it deflapped and fitted at some stage. If anyone wants it, PM me and I am happy for you to collect at no charge - will need to be deflapped, cleaned / or cleaned and then deflapped and away you go.
btw, I am based in midlands.
Last edited by Back2Alfa; 01-06-15 at 16:39.