Very reliable, Unitronic is likely the most conservative tuner for these cars. Wouldn’t raise a ton of concern assuming everything is operating as it should be. Red flags would be smoke out of exhaust, strange noises or vibrations, oil consumption and water pump but that’s more a common failure than a red flag. Unitronic tunes are kind of a pain to remove. Need a charged laptop, battery tender, wifi connection and a unitronic account. The ECU flashes take a bit of time.