There has been quite a few discussions based around this topic, around the forum. From what I gather, the 2200's are better at running on unleaded fuel than the 2000s, although it is best to use an additive.
Then as for additives to use, it depends on personal taste. 2 - stroke oil won't really do anything - apart from up the emissions. And personally, I'm not convinced those lead blocks work, apart from making an annoying rattle as you go round corners. There are substitutes, such as millers VSP, castrol valve master, reddex lead substitute, and some others. Some of these have an octane booster, and others don't. Or there's the real deal - tetraboost tetra ethyl lead, which is an additive to make proper leaded fuel - it also uprates the octane of the fuel, enabling the production of original style 4 or 5 star petrol.
Most of the substitutes can be found on ebay, although I have only been able to find the tetra boost from their own website:
http://tetraboost.com/
Of course each to their own, any owner can use whatever they want in their car, it's just their own personal preference.
I hope this has helped,
Many Thanks, Adam.
