i think they are fairly simple to fit, the 1.7 inlet will probably gain a bit of torque but your not going to notice much difference to be honest.

the frp inlet looks the bizz, but is really quite expensive for what it is, i've heard of people getting gains of around 4-8bhp with this fitted, but really it works better in conjuction with say cams, full exhaust system etc.

i've also heard the standard 1.6 inlet will do the job fine for anything up to 150bhp, anything after that is probably when you want to think about changing.