I was wondering what the exhaust recommendations were for a 1965 GTO tripower with a 400cu in motor? It has stock mufflers now and doesn't sound like I'd like. Would like to hear the rumble more and hopefully get some performance bump. What would you experts suggest? It has exhause splitters on each side of the car. Maybe I should just order the new exhaust mufflers and have a muffler shop put them on? Paul.