New T-Mag? I take it you don't mean the 'New Model Due 2007'? If its new, then don't worry about the frame cracking like others have done in the past... Word is they made improvements so it doesn't do that anymore. You'll probably get a lot of people saying about the frame cracking... The freewheel, as we all know, is normally the first thing to go. Its well worth paying £35 for a Tensile or similar. Otherwise, nothing should go wrong in theory. Still, its still quite a good idea to upgrade parts, as some of the standard onza parts make the bike feel a bit rubbish... Cheers