I bought my first focus st-2 about a month ago and it came with a set of champiro uhp1 tyres on the front (cheap tyres) and goodyear eagle f1s (expensive tyres) on the back. I've gotten a puncture on the back tyres and will need to get a replacement pair, was planning to fit michelin pilot sport 4s. Here's my question, is it worth my while to change the front cheap tyres at the same time even though they have plenty of tread to the michelins for improved grip? For anyone who has had both cheap and expensive tyres, just how much difference does it make? Will i notice an immediate difference and will the car be better to drive?