the first weak point on these engines are the rods which will only handle upto a maximum safe
280-300 ft/ib of torque so if your looking to achieve over 250bhp then you need to do the rods.
the pistons are already mahal forged pistons and should happily cope with power around 500bhp. i have heard of some running over 600bhp on standard pistons.
basically upgrading the rods should set you up for 500bhp and 500ft/ib
but to achieve over 250bhp on the auq its a upgraded turbo as the k03 turbo fitted will max out around the 245bhp mark and in my opinion your better off going big turbo like the garette gt28 which will see around 375bhp-425bhp which is a good all rounder or you could go gt3071 which can see power of 500bhp+
obviously its a lot more work than just swapping a turbo its all the intake and exhaust system to go with it all. the more air you can get in and the colder it is and the quicker it can escape the more power. a good system will involve a 3" turbo back exhaust with highflow manifold and a 3"-4" intake upto the turbo with a 2.5"-3" intercooler pipework with intercooler capable of handling the turbos maximum power so say 600bhp-800bhp try and get a intercooler to cope with the power your aiming to achieve. its not a good idea to get a big intercooler to handle 800bhp+ if your only looking to achieve 250bhp because this can cause lag.
in a nutshell the 1.8t engines of all variants have excellent tuning abilities and all take well to mods no matter how big or small everything you do will make a difference in some way.
