Ive had pretty my every type but true duals on my cougar 2.5. Its more preference then anything but the no resonator sounded like crap to me. Although the muffler probably played a big part in it. The car actually felt like it had more torque with a single exhaust at 2.25 in. Diameter compared to the 2.5 in. That was pretty much when the borla system went on my car but that things been out of production for quite some time. The actual true dual I still want to try just because but I have ALOT more to do with the cars actual need to get that much air out. Im happy with mine all except the Ypipe has no cat on it and the exhaust seems quite a bit louder with that pipe. The fake duals as you referred to I feel is more cosmetic then performance. On my car anyway it just looks right. Good luck which ever way you go.