I know what you mean, I have just put Falkens on the rear of my 1.6i and have the same issue, it had nearly bald Falkens on the rear and was fine ( except in hard cornering) but with the new ones and a set of partly worn Goodyear Assurance on the front driving it is aweful. From everything I have read I need to bite the bullet and replace the front tyres as well. Im putting it on a hoist this week to see if I have any suspension bushes that need replacing first. It will be worth it to have the car back to its old self as it's not nice at all at the moment.