Car: Acura Rdx 2008 base w/ Automatic Transmission

Mileage: 150K

Scotty + Community: I am trying to replace my turobcharger due to it having been diagnosed as failed by 2 separate mecahnics. I printed out the Acura service manual and was humming along until requiring to remove the 2 rusted bolts + 1 Nut attaching the upstream catalytic (Three-Way-Catalytic TWC) to the turbocharger assembly. 

I own and have tried to induction heat gun (Venom HP mini ductor) on the bolts but it was unsuccessful even when turning the bolts bright red. The nut is not reachable via the heat gun and I have tried all possible means with various ratchet wrenches. Using an impact gun or chisel for the location is impossible as the triangular flange hides 2 of the fasteners from line of sight.

Please suggest any tools or methods for such a challenging issue.