I had a plus model, it was a great car. I saw 150 on the speedo of mine, with plenty more to go (I backed off once I saw that figure)
It depends where you go for servicing tbh, I found that it wasn't overly expensive from a specialist.
They can be taken to over 400 bhp if you have the money, a few on fccuk (fiat coupe club) were running that amount of bhp
Some run in TOTB (ten of the best) too