I will still look into the 2.0TFSi engine as an option, its a newer engine and you can get more power out of them, but there is also the weigh up of a cheaper base car + good value performance parts vs a more expensive base car. I like the idea of being able to simply get another 1.8t engine as there are so many of them out there, plus all of the parts and combos have been tested. The 8L A3 is quite a cheap car to start out with and would be lighter anyway, I have found most first gen models of most cars are lighter before they start adding on extra weight like leather seats, air con etc etc.
As this will be a project car and a 2nd car I am not too worried if the car is off the road for weeks at a time, gives me more freedom to be able to try different things and take my time over certain aspects. Due to the lighter weight A3 vs TT it also means that I won't need to go for big power for the same performance AND the A3 is cheaper! I have read that the kerb weight for the 8L is at 1,145kg, I should be able to pull a fair amount of weight out the car by just unbolting a few things and removing items such as air con etc.
I do find it quite funny how small the turbos are on some of the cars though, the stock RX7 turbo was probably around a GT35 sized turbo, a GT28 turbo is tiny but is seen as a mild upgrade on the 1.8t. Might look at a few other options for turbos - wonder if anyone has every run a twin turbo setup running 2 K03s or something?
Anyway, just researching around different options and ideas, and as the Lotus motto goes - simplify and add lightness!