Not using the earth tab provided leaves the sensor output susceptible to RFI, specifically from the HT leads. This can give random missfires, stutters and hesitations on load. I have even seen the load register dancing around my screen when mapping once, going from the top 30psi line to the 14psi line with no drop in boost at all, so going deadly lean as a result!!

Some of the sensors didnt even have the tab so theres nothing you can do. The RFI problem has been an ongoing problem for marelli sensors for many years. The later earthed ones certainly seem less suseptive to the anomally.

Those who have tried fitting Magnecor leads to a YB will be familiar with the random missfires on load and know what i mean as these sometimes interfere wether its earthed or not.. roflol.