Re: Upgrade or change it?
I'd think long and hard before changing brand - Ive just got out of that very mistake.
I had a 147 for about 3 years and loved it, but changed it a year ago for a 1.9 MJET Stilo (same diesel unit as the Alfa uses) as I was offerred a good deal on it. To cut a long story short, Ive just part exed the Stilo (less than a year old) against another 147 about the same age.
Obviously Ive taken a hit on selling such a new car so soon, and the MJET Stilo went like the clappers - but having owned an Alfa, nothing else felt quite the same and I just couldnt live with it.
I'm happy as a pig in m*ck now though and hopefully I wont make the same mistake again!?
As for modding the 1.6 - a friend of mine had Angel Tuning out to his 1.6 and they made quite a noticable difference with a remap and new air filter system which came to about £300 all together.
Depends how much of an increase you are after I guess?
Hope that helps.