^^This. If it is toe-out, the car will dart left and right. It's possible that the new LCAs were slightly longer. It's also possible that the strut mounts are in a slightly different position, which would also affect the toe angle.
Grab a nice big tape measure and check the difference in cross-car distance between the front and rear of the front tires. Use the same tread groove on both sides (left and right, and fore and aft) It should be very close. If anything, the aft distance should be slightly larger. i.e. less than 1/8". (for slightly toed-in) This will give you a ball park number. You'll only be able to place the tape measure part way up the tires before the y-pipe interferes. Just make sure you stay roughly the same height off the ground front-to-back. Oh, and make sure your car is nice and level on the ground. Driving it up on ramps will alter the toe angle.
