So, this will be a bit of a long post, so TL;DR first

Bought a Legnum with broken transmission. Had a spare on hand and did the job. Now the car is driving, but seems to have no boost pressure and error codes 43, 72, 24 and 77. Any ideas?

Now for the whole and long stuff.

So, the car is a 1996 Pre-facelift VR-4 that seems to be a winter spec. The guy I bought from seemed to have some knowledge on cars, but didn't seem to be most familiar with all the stuff Legnums have going on them. Also the car has seen some better times as it has been fiddled with quite liberally.

Story of the car before I got it; The dude had some problems with the car getting stuck to third gear. He got a new transmission rebuilt and fitted to the car, but that did not fix the issue. The old transmission and new transmission were of different model numbers(Need to check exact numbers, but same except for ending in A and B respectfully). After that he noticed some moisture in ECU and drying that seemed to get the car going. Though problems were not at an end and next he got the rear end to lock in speed. He changes that by himself and then it came apparent the new transmission was broken and he listed the car for sale.

So all in all a lot of stuff has happened recently and all seems a bit iffy.

Still, I got the car and got to work. Turned out the planetary gear set(Not sure on term here. The part that connects to flywheel) had all it's innards smashed. I pieced together the old transmission changing out clutch stuff and seals and such. Now everything should be in place, but I still have quite a bit of problems and not sure where to look for solutions.

Some mishaps also happened during the work:
-During dropping the transmission the cables for starter motor got stuck and had some of the weight of the transmission on them until we got them out
-At first try in starting the car one of the turbo pipes was not connected and the car would not stay in idle

Now to the problems.

The car is now driving, but feels a bit sluggish and hard to move. Power steering also has some issues, but the oil for that was a bit low and might be better now that I added some. Real problem is that after driving for a little bit getting to second gear the engine light comes up. Continuing on to the end of third lunges the transmission to limp mode and the N-light starts blinking and there is a jolt. Car drives like this, but very slowly. Also I can hear a slight whistle at all times and boost pressure seems to only be 0.04 at maximum if the instruments installed can be trusted.

Upon reading the error codes with the dash method I got five codes:
-N-light: 43 (3 speed complete control of transmission)
-Engine-light: 72 Ventilation Control Solenoid Valve System <T / C-A / T>
-ABS-light: 24 Wheel-Speed Sensor (RL) System
-TCL-light: 77 TCL vacuum system or ventilation solenoid
-ASC-light: 24 RL wheel speed sensor system

So, any ideas?

Not sure on all the mods the car has as it's seen quite a bit of fiddling, but I'll list all that I know or suspect:
-Intercooler seems like a bigger one
-Bigger oil cooler
-HKS SQV4 dump
-3" exhaust after down pipes
-Turbo timer(Starbo G-12(No idea how to use and it keeps beeping))
-Boost gauge
-Reverse collision indicator and some random button for it seems
-Some random button in place of headlight adjust. No idea what it does
-Touch screen Kenwood media player that makes the speakers whine when it's not on
-Amplifier for speakers in trunk