If you are looking for opinions I can offer mine. If you're looking for someone to tell you how to waste your money then I'm not your man. Forget buying that thing if performance is your goal while passing your MOT, period. If it does not violate the inspection and you want some "cool" factor in the parking lot then buy the thing. Bottom line is you have to sit down and figure out what it is you want from your car in an honest way.
I know K&N is a well talked about company. But that does not mean that you should believe all that you hear or read. You will not get 8hp from bolting on that intake or any other one for that matter. That ad and thousands like them are based on a few things; selling as many products as the can to make money, making big claims (there is a big is better public out there) to draw in buyers, making very broad CYA statements to avoid the dis-satisfied consumers and hoping that nobody has the time/money/ desire to do back to back dyno tests to make a case against them for a simple return. Don't understand me wrong, there are ads and products that do help and meet their claims. The key to not wasting your money is education so that when you read an ad and red flags pop up (that means serious questions come to mind about their claims), and they should at times, you either have the knowledge to say BS or the knowledge to look deeper and discover if it id fact or fiction.
Fact is you have a 1.6L 8v engine which makes 100hp. That really ain't bad if you think about it. Yeah, the early Golf I GTi made 110hp from the same size engine, but it did not have to meet any emission tests and nobody gave a rats §ss about fuel consumtion then either. Fact is that for "bolt on" parts you are looking at about a max of 15% horsepower increase. Not knowing your plans, if you have any, or the in and out of the UK MOT tests it is hard to suggest anything. What I suggest you do first is this:
~ make a detailed list of what you expect from your car based on how you will drive it.
~ come to a budget limit, then add 20% and plan around that unless you hit the Lotto or something
~ list what you can and can not do based on required tests, police, your own desires
~ then start doing research and educating yourself on areas you don't know a lot about
~ part of the research/education is asking questions at places like here, but state them with some background and purpose and plans and limits and as much information you can remember to include.
Try it and see if it works for you :beer: