I went to look at an Audi A4 130TDI at a dealer this time last year, it wasn't in very good cosmetic condition so I walked away and saw a silver bora a few cars away from it. It looked good and once I saw all 3 letters on the boot were red I had the obligitory test drive and signed for her there and then.
I've had 3 Golfs (110, 115 & 130 TDI), had all of them tuning boxed or chipped so I know the differences before and after. I had the Bora chipped about 9 months ago.
Power wise the 130 is more powerful upto about 3500rpm, it's only in the 4000's that the 150 is still pulling and the 130 runs out of steam. Once chipped the 130 is more torquey than a chipped 150!
handling wise, the front end feels exactly the same whether its a Bora or a Golf but on tight bends the back feels a bit more planted on the Bora.
Interior wise the Golf has a 330 litre boot space?? (or thereabouts), the Bora has over 500 (only 2 cubic litres less than a Passat)!!!! It manages this by sacrificing a bit or rear leg room but its still ok inside.
The Bora has better clocks than a Golf (The 150 Sport has the Golf Anni clocks), the heater vents close fully and are illuminated at night. There's lots of little touches the Bora has which a Golf doesn't.
They are pretty rare though. You'll always see 130 Boras, especially silver ones but not many 150s. Good luck hunting!
Mine will be up for sale next November - The missus has given me the green light to buy a Saab 9-3 Convertible. Now I've just got to find a nice 2.0T for the right price!