I wouldn't hesitate to get the 90TSI. (Well I would from a power perspective...). My 118tsi is built rock solid with a high quality interior. I drove mine through miles of country dust over easter and from this no squeaks. I do have a rattle now comming from the interior rear seat light cluster but I suspect it is a loose light globe.
I think the very keen pricing on the 90TSI is hard to turn down yet they are still a quaity car.