I have noticed the thermostat that was in my spfi EA82 manifold was a little taller and way heavier than a 'normal' thermostat out of these EA series. Did the spfi run a heavier duty thermostat or am I just lucky ?

Ordered a T-stat, along with other items, from the Dealership. T-stat I got was quite hefty and quite different than the one that came out of the EA82.

OE type thermostats are bigger pellet and spring, larger throat opening.

 

Light weigth crappy ones are aftermarket replacements that are sub-standard to the OE.

 

IF you pulled a wimpy one out, it's not the original.