That would sound really really ricey...and if you want the flowmaster sound but don't wanna pay the price, there's a muffler called flowsound which is supposedly a flowmaster muffler without the flowmaster stamped on it. But I wouldn't run straights..you'd get a headache and ticket real fast.
i had custom 2.5 inch exhaust with cats but no mufflers and believe me it sounds pretty good until around 2500-3000 rpm. after that is sounds pretty ricey. without the mufflers you will also get compression waves coming off the exhaust valves when you decelerate from a high rpm while in gear. and you will get a ticket if the cops are dicks. i've only been warned. the exhaust will have the worst dronning sound. so just get some mufflers and a stronger sound with the v6.