Something like this....

 

I can only imagine what that sounds like on the street

 

using a larger diameter pipe for the turns helps out but costs more and itsn't commonly done.

Dave Lemon used 4" tubing for two mufflers run in series on his 13b 6port streetport racecar. all mandrel bent, fat 4" tubing high flow! of course it is LOUD but you get the idea....

 

I have heard several people say that having two pipes collecting into one and then running to the muffler(long prmaries) is the way to go. Instead of having a Y pipe connecting the two THEN running to a muffler, could you have them collect in a muffler by having them run into a single in/dual out muffler, but just... reversing it. I havent exactly chopped apart such a muffler, but would this be possible? Would it have the same effect as the RB long primary system? heh, or would it just suck?

 

Early Vipers had side pipes. Big block 'Vettes came with factory side pipes. As did the Ford products mentioned. I would have to think side pipes are pretty efficient, straight out of the headers into minimal mufflers and outta the tailpipe. However, they are probably too loud for a closed coupe.