California darty handling

That doesn't sound normal to me, if I understand what you are describing. How long have you had your Cali? How old are the tires?
Perhaps an alignment issue? Maybe something with the suspension?

When I picked up my Cali 3.5 years ago (it's an '11), it was riding on the original P-Zeros. New tires and an alignment, and it made a world of difference.
However, I would not classify it as "darty"....T

 

Might have too little toe-in, or even worse, toe-out.
Have it aligned, and if you're on old tyres, especially the horrid Pirellis or Bridgestones, have Michelin Pilot Sport 4S Portofino spec tyres put on it.
Ferrari racks are light and quick, but the car should not be darting. The Cali has understeer from the factory, as it's a GT car and not a race car.
Get the car aligned, make sure your tyres are not old, and make sure the tyre pressure is correct.
Set tyre pressure with a proper quality analogue meter that locks on to the valve with a little hose, when the tyres are cold in the morning.

 

My cali 30 had a bunch of toe out when I got it, and it was fairly darty - hard to keep a straight line. An alignment fixed it. I'd get an alignment shop to check the alignment, check tire pressures and look for any worn suspension bushings. Definitely doesn't sound normal.

 

I would also have the rims checked, over the years I have seen bent wheels (especially in front) do some pretty strange things to handling.

 

The new P Zero 4 is amazing. Objectively (i.e. numbers-wise) superior to the PS4. Of course people may prefer one over the other subjectively, as different people like different attributes.

 

I spent a day with the PZ4 on the 812 and have run them on other cars as well. I think they are nothing compared to both MPSS and MPS4S.
We've been debating this before, as I say you should compare the PZ4 to the 4S which you don't agree on. They are not related to the MPS4, which is not available for the Porto at any rate. I think we simply see things completely different in this regard..
But I will say this. I spoke at length to a Pirelli technician last weekend, and he was 100% on point and agreed that the comparison was as I said. PZero vs. MPSS, and PZ4 vs. MPS4S. He words, and I quote, "We cannot currently match the MPS4S unfortunately when it comes to wear, but we try to match the comfort and grip". That's his exact words. I asked him about the comparison to the MPSC2, and he said PZ4C.

 

Pirelli' do tend out of of round, especially if they are older and not driven as much. I am not fan, I have Michelin or Bridgestone's (except the Range Rover it has nokian winter ties because it only gets used in the snow), on all my cars.

 

New cars should come with too much toe out as dealers are supposed to set up each car to factory spec before delivery. If the car had a previous owner, before taking delivery the car should always receive certification from a dealer, like when they certify a car before allowing it to be covered by Ferrari's "New Power" warranties.

Some tires also require special set up.

If the tires are not the ones normally spec'd for the car you can experience very darty behaviour. When I owned my 540iSport 6MT I "upgraded" the tires to a new higher performance design and the tires made the car very unstable, hard to track straight. I reduced tire pressures by 2 PSI all around, contrary to the normally-spec'd tire pressures and then they were great.

It was a completely night-and-day difference and had to do with the different materials used in the belts. The same thing WILL HAPPEN if you increase the width of the tires from the standard tire sizes spec'd for your car.