I have given up on my Milltek for exactly the same reason as Joe did , the back hangs down so far,have heard that there is a shallower milltek one that you can get, but not seen any yet.
I have a pipeworx high flow one, bought it off an edition 38 member for £150 (though they are £450 new) and it sounds great, though may put some better tailpipes on it. It fits to my milltek downpipe without any issues, and isn't overly loud, but does sound quite powerful when you want it to, and also when reversing onto the drive late at night