I doubt very much its anything to do with your intercooler. People run 400bhp with the top original one.
I don't think a piping kit actually exists for an evo fmic for the gtir, so you'll need to put one together from pipes and rubber hoses/bends yourself.
And don't for christ sake just go and run 1bar on a bleed valve. If you have a problem you need to fix it first. You could fit a bleed valve and run 0.6bar, just to bypass the original solenoid to see if thats your problem.
Otherwise you need to go through the motions to find the problem. Compression test, look at your spark plug condition, make sure its fueling ok, make sure water temps are ok, boost leaks, detonation, clean your maf, check leads, watch the colour of exhaust smoke, check for oil in coolant, etc etc. Boring I know
Give it to a good garage if you can't find out.