TDI 2.0 Turbo screech time to upgrade?

earplugs?

cant help on the turbo fitment. But why dont you think about having your old turbo repaired with better bearings, stronger shafts ect. Hybrid basically. I would also think about speaking to the people who mapped your car. You will have to have car mapped again for a different turbo. You might not want to drive it either. If the turbo breaks up you might be looking at a engine build aswell!

the turbo and exhaust manifold are an integrated item - i presume (dont know) that the 170 turbo would fit.

increasing the boost or fitting a larger turbo will do nothing on a diesel without a remap - the engine basically gets lots of air (there isnt a throttle valve in the same way as a petrol engine), but the torque/power is controlled via the amount of fuel - hence the remap to put more power in and why a simple resistor to enrich the mixture can create so much extra power

a hybrid rebuild from Allard (vt2) or turbodynamics (MD375) is a bolt-on replacement but has the same hot side with suitable modifications, and a much larger cool side to pump more air, both for a given pressure and can run higher boost pressures.

a rebuilt hybrid turbo should cost about £450 plus vat exchange and about £950 plus outright brand new, and then about 3 to 4 hours labour for a turbo swap

a big turbo remap will cost about 500 or so, and you should have a decat or high flow cat to keep the new turbo cooler. some tuners might suggest a high performace exhaust but i dont think this is as necesary as the decat or high flow cat.

overall you should get about 210-220hp from the vt2, and 230-240 from the turbodynamics with a good remap, exhaust and decat.

dont bother with a performace air filter - they are worth nothing,

if you just fit the big turbo with standard map or a remap you will get exactly the same performace as a standard turbo (without the screech!) and can remap later.

The PD170 turbo is basically the same as the PD140 turbo just clocked to sit at a different angle on the engine so you will not gain anything over the PD140. The PD170 gains the extra power with different more effective nozzles and a slightly more agressive map.
Allards VT2 turbo which is no longer available was/is good for 230 bhp and i had one running 260 bhp back in 2005 on my Seat Ibiza Cupra PD160.
Turbo Dynamics do a range of hybrid turbos.
Set 1 - PD130

Stage 1 = MD345 = GT17 compressor wheel.
Stage 2 = MD446 = GT20 compressor wheel.

Set 2 - PD150
Stage 1 = MD374 = GT17 compressor wheel
Stage 2 = MD376 = GT20 compressor wheel

Stage 1 – MD374

Hi flow GT17 compressor wheel, cnc machined compressor housing, 360 degree thrust bearing, cut back turbine blades, lightening of turbine wheel for faster ‘spool up’, modified V.N.T. turbine housing, uprated turbine seals. Other ‘blueprinting’ modifications. APPROX 200 - 220 BHP

Stage 2 – MD376

Hi flow 2275 spec compressor wheel, cnc machined compressor housing, 360 degree thrust bearing, cut back turbine blades, lightening of turbine wheel for faster ‘spool up’, modified V.N.T. turbine housing, uprated turbine seals. Other ‘blueprinting’ modifications. APPROX 240-260 BHP

Stage 1 £925 plus VAT for new unit
Stage 2 £975 plus VAT for new unit

Removing or replacing the back box with a free flow version is a lot more important then removing the CAT as it`s the stock back box that is the restriction in the exhaust system not the CAT.