Random technology (racing) downpipe, LIPP elbow, and Tanabe Hyper Medallion exhaust. With that behind the 60-1 turbonetics bolt-on, it was the quietest exhaust at one of the local meets, from idle all the way to WOT.
The one guilty bit with it is that there's no cat, nor is there a way to add one without replacing the downpipe. I have a really hard time feeling too guilty about that when there are so many diesel pickup trucks out there with the big-ass side exit exhausts, and chipped so that they'll fill my car with soot at every intersection if I happen to be beside them at the light with a window down. They're not as bad for carbon monoxide because diesel simply isn't bad that particular way, but just as bad for NOx and several times worse for HC emissions, enough so that they'll emit more on a single heavy throttle start than I will with my entire tank of fuel. This also takes a lot of the joy out of driving around with the roof off in this city. (We seem to REALLY like our diesel 4X4 trucks up here.) It's impossible to make any kind of difference even in my own neighborhood.
Local regulations actively make it difficult to install an aftermarket catalytic converter, and it's even been implied that I could be fined for having an aftermarket cat, but not for complete removal of a non-functional OEM. Yep, that's right. Replacement with an aftermarket unit is an offence, but removal of the OEM isn't, so long as it's within reason that the OEM unit was no longer functional. For a vehicle more than 15 years old, you don't even need a mechanic to sign off on it.
That said, just to see, I did run my car through an emissions test in BC. The car actually passed the tailpipe tests for being a 1989 model, with HC, NOx and CO emissions below the acceptable standard (Though it was close for the NOx number), but of course it failed the visual inspection because there isn't actually a catalytic converter anywhere in the exhaust. Didn't matter, because I don't need to register my car there. It's not long at all before my car hits 25 years old, and I'll no longer need to worry about it even if I did move there. (In the meantime, the trees in my own yard have me at a net positive for city smog, even with 4 household vehicles.)
Should I install a cat? Sure, all else being equal. It's not.