Good to see the matiz is still alive and even getting better and better :)
Very nice whistling sound btw.
Do you have pics of the exhaust? I guess its fully custom from front to back, right?

Exhaust is not yet finished but yeah, fully custom stainless steel. (for now only the downpipe is fabricated),

Primary turboback will be 50 mm, catless, with Borla mufflers.

Add to that the wastegate exhaust, open 35 mm pipe.

With the open wastegate pipe, I've estimated this setup to flow up to 200 hp so I have enough headroom for future increases in power.

The whistling sound is from the billet compressor wheel and yeah, I have to say it sounds even more awesome in real life!

So you're saying the sound changed by replacing the compressor wheel to one that's billet?

Yes. The stock wheel (cast, 5 blades if I remember correctly) had no whistle at all. This one was custom built to fit my turbo and it's pretty much the same design that you find in newer generation turbos.

Something to do with the wheel design and harmonics (not necessarily the number of blades).

So what pressure you doing now ? is the IC not to big for this setup ? is there any lag ?

For now it's set to about 7 psi.

TO start with, I'm aiming for 100 hp, I think it will be achievable with about 10-11 psi.

IC is pretty much spot on for this setup, it's actually the smallest aftermarket IC I could find.

Turbo seems to spool earlier than before, which used to come into boost at about 3200 rpm measured on fourth gear.

We'll see exactly after the tune, but it seems that the results I wanted before this setup have been achieved: more flow at the same psi while decreasing spool time.

This is a urban legend that still sticks in the turbo mod community. If you calculate how much air in just a one second wanders through an engine, you realize that an fmic with a couple of liters of volume takes absolutely not a lot of time to get filled. Of course, too big is still possible - but then it would have to be a really really big fmic.

Example to show the dimensions I am talking about (efficiency losses are neglected here to keep it simple):

1 liter engine = 0.5 L of air per rev.
0.5 bar boost = 1.5 times the amount of air
@ 3000 rpm = 50 rounds per sec.

50 rps * 0.5 L * 1.5 = 37.5 liters of air per second

You can see that even an intercooler with about 4 liters of volume gets filled in almost a 10th of a second here. And I guess his intercooler isn't even that big :)

I read you have calculated that safe boost is 4-5psi do you not worry about motor issues ? More interesting is it still complying with emission standards like CO/CO2/HC have you test those ? as I seen removed first cat don't know only why if can be done nicely with first and second cat ;)

I've found another matiz from poland running 15 psi for more than 50000 km on stock engine and gearbox.

Low compression ratio from factory helps achieve that. It has 9.3:1.

Both cats were deleted however emissions are not an issue, I can bypass that, this exhaust setup was made to handle big power instead.

Intercooler specs from the manufacturer:

For vehicles with displacement at 0.8-1.5L
．Dimension: 430*135*51 mm
．Weight: 2.6KG
．Diameter of Connector : 50 mm (O.D)

Have you taken injectors from another stock car or are they custom ? My idea was to get IC from astra G 1.7TD ;) , turbo will be gt15 from VW polo AFM motor code