So are you still using the overboost cutoff switch that was original? I believe on the non-IC cars, it was somewhere around 8. The IC cars were at about 16 psi. They can be adjusted, but I don't know if the nonIC ones can be adjusted all the way to 16 or beyond.

I would try this, just to see what is going on. Oh, first of all, how are you getting your boost readings? Are you sure it's accurate? 7 psi sounds ok for non-intercooled. Try removing the hose from the wastegate actuator, just to see what happens. In worst case, you will just hit the overboost switch. At least then you will know you are capable of getting more boost.

When you hit the overboost switch, you will know it, there is no mistaking. The engine stumbles and comes back to life after a second. You haven't hit that point yet, right?

I think if you had a massive boost leak, you would not be able to get to 7 psi at all. Big leaks should be easy to find anyways, just poke your finger thru the hole.

There is one thing you can try to check the cat. There should be a test port in the exhaust pipe after the turbo and before the cat. Remove this plug and see if the boost comes on faster and goes up more. If it does, then your cat is probably stuck up.

Greg