The forst batch where spot on!! But they where made by a well known cam specialist, the second batch where ballsed up as sam took a set of the first batch to another company who copied the desighn wrong. it was an atempt to save production costs and make more money that bit him in the arse big time!! Batch one are awesome (i run a set) batch two did have repkacement exhuast shafts sent out that should of sorted the issue. i wouldnt go near the sets that dont have the replacement cam as the machining costs wont be cheap. the issue is the locating pin for the cam gear was wrong which fooked the whole cam timming and its not as simple as just making a new pin as its a billet cam so is made frome one piece. if you search tgtt theres bucket loads of info on them and the issues the caused. shame imo as if sam hadent skimped out on costs they would still be available and probably one of the greatest mods for bigger spec setup. i love my ones