the rods on the 1.8t arnt weak by any means, there just not strong
If you want big power and reliablilty you really need to do some changes, rods, bolts etc.. the rest of the engine will be fine generally, im not sure what the pistons are limited too, they are very light in these melt easily, but if its set up correctly that wont be an issue, even with bigger power.
but... if you run a K04 the rods will be fine generally, its just down to the level of boost your running, us passat guys often run the garrett setup on stock rods and i have never heard of one failing yet, but generally if you go to that sort of effort, internal engine changes go hand in hand, its the compromise between power an reliablity again.
