You know why they call it a "punch gearbox"? 
You've gotta go from D to 2 or 1 and rev the engine to an inch of it's life to get the feeling the actually has a turbo 
Coming from a guy that has owned a 156 before I'm sure that you're looking for something easier and cheaper to maintain while still being performance orientated and have a level of refinement above the typical japanese grey box C-segment. Plus you're thinking about the TDCI so I can see your line of thinking 

2006 VW Golf GTI - let's not beat around the bush you're looking for a powerful car on the cheap and relatively cheap to maintain then this is the car you should be looking around for, GTI's are very popular and are sometimes as common as a Toyota Vios this is bad if you want a unique and rare car but good when it comes to maintenance bills as with the number of cars on the roads it makes sense for stockist to import cheaper parts to cater for people that want to avoid the expensive prices of parts VAG Malaysia. For a performance orientated car it is relatively cheap to maintain (do note on the 3 points below);

Few things to remember about buying this car.
1. Gearbox - The DSG dual-clutch gearbox is generally trouble-free, but the Mechatronic ECU that controls it can fail – a clear tell-tale is lurching when you pull away, where it should be super-smooth. The manual gearbox is bombproof. Ballpark price for this thing is about RM5000 
2. Engine - The turbocharger's dump-valve diaphragm can split, meaning you won't feel the turbocharged kick at 2000rpm, performance building more lethargically instead. You can fit a replacement from the Audi S3, which uses a plastic piston rather than the Golf GTI's rubber diaphragm.
3. Suspension - The Golf GTI is, of course, front-wheel drive, but it can wear the inside of its rear tyres, to the point where the outside edge has plenty of tread, but the inside is down to the canvas. This can be due to the rear shock absorbers becoming weak – if so, you'll hear a droning noise, rather like a worn wheel bearing.

Here are some buying tips from Evo magazine.

2006 Skoda Octavia 1.8 Turbo - from around the same time period the bigger D-segment saloons such as Skoda Octavia, Audi A4 and VW Passat were all using 1800cc turbo engines but without a DSG gearbox, they were using an Aisin sourced 6 speed slushbox gearbox. The engine and gearbox might seem ancient tech to what they have nowadays but it is much more reliable than the DSG 7 speed. Even though Skoda can be considered a dead brand in Malaysia the franchise holder for Malaysia Berjaya Motors still keeps Dunia Prestasi service centers up and running to cope with any issues Skoda car owners might face, even-though they mainly focus on selling Foton brands of cars nowadays so no worry if outside workshops can't handle the issue you can always bring it to DP but of course prices going to be high  but because the Octavia, A4 and Passat have so many parts in common you usually won't have an issue getting parts for this car -- had a TT session with the owners club which is a small group of like minded guys sometimes drive down to Singapore to get things done or ship parts from china via Taobao.

Just incase you're wondering which Audi A4 and which Passat, refer to the pictures below 

what was owning an alfa 156 like!?

i was very keen on getting a manual 156 v6 last time.... maybe it was a good thing i didnt....