Friday I had Centerline’s header/catalytic converter (PH 120C) installed on my 1983 GTV6 (original owner). The header assembly is top quality. I did not put it in but had a friends auto shop (Cache Valley Automotive) do the work. No drama on the installation. I could have done but don’t like working under a car on jackstands. Also it’s awful cold in my garage (Utah). Me car has after market C&B cams in it so I thought the headers really improve performance. I have not driven the car much so really can’t comment on performance but maybe latter this week if weather holds I can drive it. It’s inthow much sound is depressed by the cast iron headers. I suspect to get optimum performance I will need to get the car retuned with its new configuration. That will have to wait until spring.