My 2009 Corolla's Catalytic Convertor got choked at 52000 km, even though i used mix of Hi-octane and super in Islamabad. Got it cleaned from G-8 silencer walla for Rs. 2500, by blowing air through it. Brownish powder comes out. Keep blowing till powder stops coming out. Before cleaning, engine performance was very poor and fuel economy got worse. Now both are ok. Mechanics tend to mislead you. One chap (supposedly Toyota expert) in F11 suggested to change the clutch, etc etc.
Some of my friends got their CatCon removed, but I dont recommend that, as it can result in more noise, pollution and possibly computer problem. Cleaning is easy and the recommended method.
I would like to hear from others what their experience was and how they tacked the problem, and at what cost.