straight pipe Vs Mendrel Bent sport exhaust

[Ford_allen]

hi guys i have a mendrel bent spor exhaust system on my ford ba 6cyl but i wanna get smt abit more loud. and imnt good at these technical stuff. i went to couple of exhaust shops and i was told they could change the rear muffler to straight pipe and there would be one spor muffler in the centre muffler and there would be 2.5 inch straight pipe instead of rear muffler.do u guys know that how this would effect the car goes? do u think like i can end up lossing some power?or do i have to get my car retuned?as i heard i could end up lossing back pressure?