I think any "Y" type exhaust is going to be loud on a V6 - my turbo mongoose exhaust was, but probably not as bad as that ebay one (which tend to favour the "loud and proud" boy racer types most of the time?). Single large boxes (as with stock cars) seems to work best if you're after something ok for every day driving - the magnex na box I replaced the mongoose with was a LOT quieter at idle and low revs, but still sounded nice higher revs. Sounds like you are after something in the middle somewhere.

I have the old large full length exhaust off the V8 in the house I'm still not sure what to do with yet. That's twin pipes and front silencers going to a single large box at the end. If you were closer (and in the uk :) ) you could have seen if you could use any of it on an mr2.