Re: ITB Conversion on sixteen valve 4AGE On my stock bigport AW11 a leaking exhaust manifold gasket triggered the O2 sensor to go through lean and it pumped fuel into your motor. Fuel economic climate plummeted until I sorted it out.4AGE 20v ITB vacuum Directions on Intecracing.com can't help with all the rest of the pipeing as it's a bit bewilderi