Just sharing my experience with Silverstone Synergy M5 215/45/R17. Came with my car when I bought it from previous owner, had changed just 4 months before, so I stuck with it.

Previous owner changed in Dec 2013, tyre mfg date is Mar2013. 1 cracked side wall, 1 bubble tyre, 1 puncture, 1 almost cracked side wall. Here are the pics:
http://pho.to/9y3Qj

yesterday changed to Hankook Ventus2 Concept2. RM250 each at Eneos, compared to 300+ at tyre shops. Was choice between that and Dunlop Formula D05 at same price, but Dunlop no stock so went for Kooks as I dont wanna wait until all my Sh*tstone Synergy letup.

Info:
www.autoexpress.co.uk/accessories-tyres/91870/tyre-test-2015-results-by-category

www.autoexpress.co.uk/accessories-tyres/91862/hankook-ventus-evo-2-review

www.hankooktire.com/global/tires-services/passenger-cars-tires/hankook-ventus-v2-concept-2-h457.html

Obviously no comment as yet on the kooks, a wee bit noisy, but to go from ultra-crap Sstone to this is like moving light years!

TL;DR: I don't know why Silverstone is allowed to be in the market. They literally endangered my life. All the reviews I've read are crap.

Specs for kooks V2C2: 215/45/R17 87 V.

Another interesting read:http://www.tyrepress.com/2015/03/tyre-test-results-mock-european-label-ratings/
Seems like no one can come up with proper methodology for tyre ratings. Always anecdotal; yea seems quieter, yea seems faster, yea cornering seems better. Give me data or nothing, bro. The above AutoExpress review was reasonable, I see its well quoted here. Conti still wins, but Kooks not bad price to performance value.