Abduragmaan, I've being doing some 'research', well looking at old threads on the R170 forum and elsewhere as I've bought another S/C to port, I'm porting it differently compared to the current ported one that's on the car at the moment and naturally boost pressure and IAT's were the focus points in those threads. Below is a few of the points mentioned.
The bottom line to make 14 psi + @ the T/B the ECU needs to be remapped no matter how large the crank or how small S/C pullies are. See this thread by SweCaliber (Eddie):
Kompressor BOSCH ME2.0/ME2.1 ECU "Boost limiter" and how to remove it without Maf clamp. INCLUDING READ AND FLASH GUIDE! | Mercedes-Benz Forum (benzworld.org)
Basically, the 'Boost Limiter' has to be removed or fooled which I suspect is not allowing you to hit higher boost pressure.
Note in post No.13 in the above thread what Eddie says about using a larger diameter exhaust., boost pressure decreases and power increases.This outcome is well known in S/C circles.
The 'limiter' is the bypass valve controlled by a combination of signals via the ECU for engine speed, throttle position and air mass (MAF voltage).
If you don't remap and still want max boost, you'll need a MAF voltage clamp that actually clamps at the correct voltage. It seems that can be anywhere between 4.5-4.8V, some trial and error required, I've adjusted mine from 4.7v down to 4.6v and all is good - no bypass valve opening and no S/C disengaging.
Another aspect when looking for 14 psi everybody including myself refers to R170 threads and information scattered across the Internet as that car is by far the most popular to modify when it comes to the M111 2.3 (M62)
What's not taken into account by W202 owners is the fact the R170 was sold as a sports car and I suspect the stock mapping might be different to the W202. And then there's two W202's early and late one using ME 2.0 and the later with ME 2.1, so there has to be map differences along with different inlet manifolds and throttle bodies. Also, the R170 has a larger stock intercooler compared to the W202, and the R170 also has a different engine designation 111.973 whereas the W202 is .975. The guys with R170's seem to get better max boost pressure, 14 psi has been reported many times (without remapping the ECU) while using 218/220 mm crank pullies and 86/87mm S/C pullies along with a MAF voltage clamp than guys doing the same with W202's.
The most boost pressure I'm aware of for W202 is between 12-13 psi judging by the info I've read, probably closer to 12.
The only W202 that I know about that produced over 14 psi was SweCaliber (Eddie) car, which he converted from ME2.0 to 2.1. There may be others, but I don't recall hearing about them. Currently I've only got max 12 psi and I'm still using the stock I.C. plus several supporting modifications.
The bottom line I reckon for you to see above 0.8 bar/12 psi is to get the ECU remapped. What would be interesting is if you refitted the stock I.C. and got a proper MAF voltage clamp and the checked the boost pressure. One other thing, I found using a BAR boost gauge is not great to get an cexact boost reading, you're better off with a PSI gauge as we're only talking about 2 psi different between 12 and 14 psi. Beware too and it's been reported several times that stock air filter and box is a restriction when chasing BHP, I see you don't mention anything about your air filter setup.
Just my 2 cents worth as I could be wrong on several points.
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