Idrees has just put a For Sale thread up with a very cheap 4E, get it bought http://www.ukstarletowners.com/topic/103044-garage-sale-aftermarket-oem-parts-cheap/?p=1191940
As long as you've fitted the copper sealing washers, they dont need to be mega tight. Thats all it is, people treat them like a normal bolt and ping it goes. And there is that I suppose lol.
I know I had a similar issue but this was due to the added stress of the new cover plate causing the cylinder to pass. Once fitted with new it was spot on, gear changes were as if it was factory.