Get some proper size holes in it, 110 nozzles are only slightly bigger, I've got a huge boost with my big ones and no smoke to speak of. What engine have you got? AGR, ALH, AHU etc, that can make a difference to what you can get. The ALH with .216 nozzles (T4 ones) and a tune you can get 150 odds because of the vnt turbo but if it's a wastegate then you're limited to around 125 ish. The engine code should be on top of the timing belt cover.
My nozzles are .232 and good for around 180 but I'd need to do a vnt conversion and use some hybrid version of a vnt 17 but then you're looking at a more expensive clutch and brakes. The sachs VR6 is good for the 150 with the vnt 15 from the ALH though.
The cheapest mod though you could try is the evry mod
yep agreed if your being cheapie then the evry mod and hammer mod are two possibles for a little more performance. A car of that age is probably not worth spending alot on so some simple stuff like above can help a little.
How's your intake? Mine was fairly clogged when I got the car but a good clean out and new air filter really helped especially up the revs.
What is you want to get from it though? Why not a remap or bigger injector nozzles or both? The bigger injectors have given me around 20-25 hp and a good dose of torque, well worth it to me. I do intend to get a vnt turbo and tune at some point too. I don't care that my car is older, it's been really reliable, I get 45-50 mpg while still driving between 80-100mph, I don't have to put up with a crappy dpf or any of the other modern gimmicks that seem to cause so much trouble. Yeh tuning boxes are a bit pants, the evry mod is much the same thing but a lot cheaper but if you want any decent power gains then you're going to have to part with some money. Injectors, remaps, turbos etc. It's the only way to get anything worth having powerwise.
If you have a vnt then you will need bigger nozzles and a remap, there's no other way you can get 150bhp. Your standard injectors can't supply the fuel required and your standard map in the car needs to be altered to up the boost to burn the extra fuel to give you the extra power. If you don't have a vnt turbo as standard then you wont get 150 bhp, the wastegate can't go further than 130 tops. Do you understand how the tdi engine works? You know that basically you NEED more fuel but in order to burn the fuel you NEED the extra boost to increase the combustion pressure to burn the extra fuel. The only other way is to go manual but you'll need a different pump and also a hell of a lot of searching for the info to do it and it'll cost you more.
157 at a push is the absolute max I've seen so far from a vnt 15, you have to be wary of claims of power, some people tend to exagerate, it's part of being a man lol. That's why women park so far from the kerb
You could change from a waste gate to a vnt, there's a bit of work involved but it's done often enough. Our wastegate works on pressure to open the actuator but the vnt uses vacuum so you need to rewire the N75 and also load the appropriate software into the ecu. You also need the down pipe to match too and maybe the manifold depending on what fits what.