Yes, the Thermomaster chip requires a special 160 or 180 deg powerstat (the only difference between it and the StreetRunner). As far as which one to get, it depends on how cool you want your engine to run. The advantage of the Thermo is that the new 'stat will keep your engine running cooler, giving it better performance due to the increase in cool, dense air running through it. The only problem with this is if you already live in a cold environment (like Iowa) you definitely don't want to go with the 160 deg and you might not want to run the 180 (even though people in PA and MA use them). I can't help you there. I live in NC and don't have to worry about it getting too cold for too long (just like to rub that in on occasion). Hope this helps.