The 130,150 & 160 all share the same block and head the only differences are the bolt on parts like the turbo, injectors, inlet system and then the software.
most people who wish to achieve high power go down the route of:
- decat
- straight through exhaust system thus removing the back box
- hybrid turbo (using a full substitute unit or modifying their own) to spool faster, more aggressivley and produce higher boost pressure, substitute units like those supplied form darkside have a custom made tubular manifold but modified standard units utillise the original.
- remove the EGR cooler and pipework
- remove the EGR/ASV assembly from the inlet system
- fit larger diameter boost piping made from stainless steel with silicone joints
- Larger intercooler (although the 150 and 160 both have large front mount intercoolers already)
- Higher pressure map sensor
- replacement dry panel filter such as a green cotton
- smoothed air box to remove the grates
- cold air feed from one of the fog light grilles
- metal intake pipe from the skodas or vws (as most seats have a plastic one?)
- remove the PCV system and run it through a catch tank and blank off the intake pipe opening
- fit the larger oil cooler from the passat 130s
- larger port injector nozzles from bosio or similiar
- stainless braided fuel pipework
- larger valves fitted
- head and inlet manifold ported and polished
- H-beam conrods
- water/meth injection
- a suitable custom remap to alter all the perameters
there are 1000s of combinations and 1000s of different opinions these are just what i can remember off the top of my head.
There are too many different companies to list who produce these products but others will comment on their preferences.