Hello, i've just got another GT and its not runing the best its sounds abit ticky when drivng around but not on boost and its backfireing like a gooden a mean it sounds like a gun shot i put 30quids worth of petrol in it and got 65miles before a refil and a wernt hammering it everywhere so that cant be right, just had full service and mot, any ideas? can give more information and photos cheers