I've got a 355 speedo problem. Same as 348 for fix?

So as the title says I have a 1997 F355. Speedo is about 18 mph off. Checked pattern and Hz at sensor and speedo head....all the same both volts and HZ. Sensor is new. Verified the speed difference on our shop dyno as well. I saw a post a while back that used a 12 o'clock labs chip to correct this. I am just curious if that write up would be the same for a 355 even though it was for a 348. I am thinking it is. I also thought to ask if that vendor has a "Ferrari specific combo pack" to correct this problem. Thanks.