I have a WRX STI in Johannesburg South Africa.
In Johannesburg the highest Octane Unleased available is 91. This is not even fuel !
In South Africa the catalytic converter is not required.
1.) Can I change the exhaust thus removing the cats ?
2.) Which is the best after market exhaust to purchase ?
3.) Will the new exhaust effect the back pressure and thus cause the turbo to overspin
4.) Is there an advantage in changing the exhaust especially that I am running 102 Leaded ?
5.) Where can I get leaded oxygen sensors ?

I wonder if this guys fuel just killed his car and he's just not been bother with it since?