Re: Interesting mods to 3.0 GTV
I am really not sure about the unleaded to leaded conversion.. engines developed specifically for unleaded petrol don't like running on leaded as they were never designed for this in mind. I would not want to risk such a conversion if it were my engine on the operating table! The golden rule with engine development is "if it ain't wrong, leave it alone!".
The best solution is always the non-invasive one, I recommend you buy Octane booster fuel additive to increase the RON number of the standard grade at the pumps. This will achieve the same results and cost you 1/100th of the price!
Additionally, if you were to change cams, it probably would be best to consider Colombo e Bariani cams specifically developed for the 3.0L as opposed to 3.2L items as the GTA cams were designed to run with a bigger engine capacity. Chances are, the C&B cams will run just as well with the standard engine mapping (I would recommend getting this fine tuned though particularly if you were changing the induction system).
Again, induction-wise, most 3.0L owners leave it well alone as the MAF (mass air flow) sensor is very delicate and tends to be upset by something as innocent as a high-flow replacement panel filter. At £200 a go, it is a very expensive item to keep on having to replace.
If you're really that keen on getting more power I would recommend getting your engine bored out to 3.5L (the limit with the Alfa alloy block is 3.7L). As the Americans always say.. there is no substitute for cubic inches! Autodelta selling ready-to-go kits for this kind of conversion.
Hope this helps,