90 spec ones aren't better than prior in relation to power but imo they look better due to the different front bumper & different rear spoiler. engine size doesn't really matter. depends if your going to get a bog standard one and build it up or whether you want to buy one already tuned. If you build it up it can work out expensive but you do feel a sense of achievement knowing you've got it how you want it. If you buy one that's already been worked on you need to know how many miles its done since the engine was rebuilt (if it has had one) and make sure it's been kept serviced & set up regularly. If you do get one either standard or worked on there are plenty of mapper tuners about Stu, Karl, Jamsport, Engine Advantages etc who are all more than willing to help you out & offer any advice & info you need

HTH