My input...
CDL block (best block)
K04 turbo ( adjust actuator, makes you hold boost longer ( you could set it to 30psi top end but it would not make it as it blows the westgate open))
90mm downpipe, then 3" (best you can get)
Loba? HPFP ( APR people say, but i run the cheap option and has not failed me)[/
CAI? Type? Air feed location? ( I have tested a evom intake + having no intake and it makes the same power)
Water methanol injection... ( stage 3 snow kit running duel, with tb spacer. Gives a better spray)
Throttle pipe ( BSH )
Intercooler...type? THS < same + remove ac rad
Hosing... - NEUSpeed pipes
Catch can or just BSH PCV fix? ( i run a catch can just to catch excess meth)
DV...stock or aftermarket? Forge Oversized? (Stock Dv works fine no need for anything else)
Boost controller or ECU control? ( ECU also does the job fine get far more control)
Porting? ( someone done this and made an extra 10bhp)
LPFP upgrade? ( 100% needed over 390bhp unless you decresse the torque) (RS3/ttrs pump works well)
competition gasket and head studs needed? (not needed for k04)
Runner flap delete on intake manifold? ( No point for k04 - only for big turbo)
Spark plugs..OEM or NGK's? (Nology silver)
Internals needed? Pistons and rods or just rods? ( CDL take everything the k04 can give)
Camshafts - (might get a extra power top end)
I think the max you will get is around 390-430