Well, this is my shortlist so far, together with some notes compiled from this and various other threads...
* Tanabe Super Medallion Touring
Probably the quiestest, very little restriction, but maybe sounds too mild?
* Tanabe Super Mediallion Hyper
Louder than the Touring but quieter than the Racing; possibly a good compromise, but this exhaust is a bit of an unknown. The silencer does look nice and chunky though. I've still yet to find anyone that actually has one.
* Blitz Nur RX
Definitely a lot quieter than the Nur, but I've been told it's quite restrictive (?) and hangs very low. On the other hand, I had a Nur Type R on my old car and that wasn't too low. Is this one lower?
* HKS SuperDragger
Sounds fairly stock-ish, but still quite meaty. Again, I'm told one of the mountings can hang very low. Also, unless you get a 2006 or newer one, they rust to pieces within a few years. (Only the new ones are SS.)
* GReddy Ti-R
Don't really know much about this, except Nic likes 'em and it does sound quite nice, if the sound clip is anything to go by. I think it's got a nicer tone that the Nur RX and is less 'droney'.
* TRD Exhaust
Don't know too much about this one either, but I'm told it's quiet. And it's TRD... Can't be bad, right?
I've also read posts where people have changed exhausts on decatted cars and subsequently lost loads of boost. Am I likely to find this problem, or is this a non-issue with the boost controller? (I have noticed a drop in boost with the removable baffle in, even with the boost controller set to 1.4 bar.)
Will changing from a 4-inch BL to a 3-inch (like all of the above are) have any significant effect? Could it potentially mean remapping?