355 custom exhaust

I'm ready to start modifing my 355. I want to replace the entire exhaust. My plan is to use something like Fab Speed or agency power 360 headers as the start. I'd cut the back flanges off and tig 2.5" v-bands to them. Then build my own by-pass pipes and then use a generic stainless straight through muffler. Ditching the low speed exhaust completely.

With headers and basically a straight exhaust is it going to drone incessantly? The stock exhaust is not loud enough for me, but I don't want to change the tone, only the volume. I know the pipe diameter is going to influence the exhaust volume, but I also want to make sure I use pipes big enough to flow what the car needs. Are dual 2.5" pipes enough? Are dual 3" after the collectors too much? There is a lot to be said of "optimum" exhaust design, but I want to compromise as little possible. I am not interested in buying off the shelf 355 stuff either.

Any hands on experience would be great.