Don't do anything until this is fixed.

How the hell do you get Torque Steer on a rear wheel drive car?
You guys getting special rear wheel steering MX-5's in the States?
Or you drifting the car EVERYWHERE?
;)

Seems to me that you have conflicting requirements. If all you care about
go-cart "feel," then pumping up the tires will have the biggest effect, and
the alignment will be almost irrelevant. If you want to autocross, use the
special alignmnent, gumball tires, and appropriate (pretty high) pressures.
If you want good performance on the street, and reasonably even wear, use
the stock alignment and pressure, and performance street tires.

Note that until you have driven racing tires on the highway, you might want
to be careful about saying that you don't care about twitchiness. A set of
Yokohama A032R tires will cure you of that theory pretty quickly...

Read my alignment page. Don't go to an alignment shop until you
understand it (but feel free to ask questions here). The important
points:

1. For even wear, the alignment must match YOUR driving habits. I offer
suggestions for a starting point, but there's always a terminology
issue: what's "brisk" driving to me may be suicidally fast to you--or
vice versa. I spent about $400 fine-tuning the specs for my own
situation, but if you're lucky it will make you smile the first go-round.

2. Observe the order of adjustments in my article. Both sides must
match, max variation 0.1 degree.

3. If it ain't ballasted, it ain't a precision alignment, because you
don't know how it will change when you sit in the car. But it *will*
change enough to change the basic feel of the car.

4. If the technician gives you any crap about custom specs or excessive
wear, just leave immediately and keep shopping until you find a
competent garage. Life is too short to argue with fools.

Rotate performance tires at every oil change (3000 miles), all-seasons
every other oil change. I got 15k wonderful miles from a set of
195/55-14 T1-Ses, driven pretty hard. At 28 psi, they wore evenly across
the tread, and all hit the wear bars in the same month.

Go-kart feel: you can get that easily from a Miata, though you may soon
decide it was a stupid mistake. All it takes is giant swaybars and stiff
springs/shocks. However, if you actually want good handling, tires and
alignment are the place to start.

Seem to me your alignment was fine.  If your latest tires float
all over the place, I would just ignore what their wear pattern is.

Based on the other tires, personally I would guess the problem is with
the junk tires yielding so much their edge is exposed.  In short, if it
were me, I would replace tires, not alignment.

Actually, I was talking about good straight line grip.  All things
being equal (they usually are not), rubber works better the lower the
pressure.  But on thinking it over, the junk tires probably help on
the straight line since they are flexible enough to completely ignore
the camber of the wheels and meet the surface flat.  So I am no
longer surprised.

Be careful with the numbers.  Apparently, Ziex tires with slightly
different numbers are very different, believing the reviews.

Frankly, I think you are not going to get a satisfactory answer on
the question as posed above.  At least I cannot imagine anyone
being able to analyze the issue and produce the optimal (versus an)
answer.

For what it is worth, my non expert take on it is:

1) You are not going to get any real life time out of performance
  tires.  To go for a "Save the Tires!" alignment with performance
  tires you get the worst of *both* worlds: lousy handling and
  only marginally improved short life span.

2) Getting a *good* performance tire, (not the ones you have now,
  but don't ask me for a recommendation), you need to make a
  decision whether you want handling or performance.

a If you want handling, look at Lanny's page.  I just looked at
  it myself once more, and I am a believer.  They are technically
  sound and agree with my own impressions.  Note that I am *not*
  a precision driver by any means; I am not going to argue about
  a few tenths of a degree.

b If you want long tire life, set camber and toe to zero and drive
  like you grew up in Tallahassee.

You might get a meaningful answer in this group from someone for the
question "What is the best tire and alignment  to get the best street
performance, blast the cost?", or "Can you tell me a tire that lasts
many miles gently commuting, and good rain and straight line grip when
needed in an emergency?" but not on "Can you give me alignments and
performance tires that produce incredible grip while lasting a
long time?"  Any good answer to the last question is *equally*
bad, since what you gain on one part, you give up on the other part.

Leon