c. The 16 valve engine breathes much better than the 8 valve (which is why
just about every Japanese turbo engine is 16v -- ultimately it'll make more
power.
It will make more power but have less torque at lower rpm unless you have some kind of variable valve timing actually. Pre VVT Porsche used to race 8v turbo engines for their increased reliability (less valves) and more useful power at low rpms.
Obviously once VVT appeared all that changed...
16v engines flow much better at high rpm and essentially move the power band too.
Of course the FIRE 8v was never designed to be turbocharged and the Tjet was so it will be optimised far better in many ways. Also I think If you were really going mad on an 8v turbo the 1.1 is a better option due to its shorter stroke (more revvy, less stress on the crank), however it unfortunately doesn't have the piston squirters...
Also people have managed 130+hp reliably without any issues. Tricker managed it with a far less sophisticated management system than most use now many moons ago. This is especially possible if you run duel maps and have closed loop boost control.
If you want 200 hp go for a Tjet though, that's a crazy expectation from a reliable 1.2!
I'm waiting patiently for honeymonster to get his car done as i'm interested in
how this det3 thingy he has performs.
You mean that buggy piggyback thing that will never work..

The only thing that will change is adding a boost solenoid and then altering the map to suit. The DET has been running the engine for months perfectly I use the car nearly every day. It's supplying the timing and the fueling with complete and accurate adjustment including warm up enrichment and all the essential bells and whistles to tune an engine. What is left to prove??

However, yes I need to pull my finger out and get the car done before it starts to get really cold.
As for forged pistons...
When I said pistons before I of course meant pistons and rods, who an earth would run forged pistons with standard rods. :nutter:
But essentially for 150hp reliable for regular use I'd say some good flow work, balancing and high build tolerances with forged pistons and rods, the right sized turbo, a well designed exhaust and inlet manifold, and finally well set up management wouldn't be a huge problem unless you ragged it constantly.
However finding the right bits is of course is going to be the real problem as you may have already noticed. None of this stuff is off the shelf, you need to work out what you need then either make it yourself or get people to make it. Then pay to have stuff balanced and flowed or attempt an amateur job yourself.
Really if you want 150bhp plus you'd be silly not to consider the Tjet. It's all there done for you.
The task of fitting it still won't be simple though, nor will wiring it and setting up the management. You'd still need to do this on an 8v regardless though.
There are easy cars to buy bits for and do good turbo swaps on, the Cento isn't one of them.
If you want forged bits and turbo kits off the shelf buy something more popular, otherwise be prepared to spend a lot of time, money and do a serious amount of research to achieve what you want.
For research there a plenty of good threads on Fiat forum and smokeme's website has some really useful information. Other than that you'll need to read lots of material that's not specific to Fiats to be able to work out the specifications of what you need and want.